It was 7.40 on a Sunday night when 16-year-old Kevin Hicks popped out to the local shop. He had a cookery exam the next day, and the family had used up all the eggs making yorkshire pudding for supper. The shop was a short walk – you could see it from his bedroom. Kevin left home with £1, and told his mother he’d be back in a few minutes. That was 29 years ago.

On the mantelpiece of a dark, winter-lit room in Croydon, south London, there is a photograph of a handsome boy looking ahead to life. “That was taken three weeks before Kevin went missing,” his sister Alex says. Her home is full of mementoes: his favourite cassettes (Madness, Survivor, Japan, Yazoo); the jumper he is wearing in the photo; his Co-op uniform; his Crystal Palace scarf.

Alex was 14 when Kevin went missing, and for years she wanted nothing to do with the campaign to find her brother. She left that to her parents. But now they are both gone: they died prematurely, heartbroken – her mother aged 47, her father at 57. “My mum did an appeal a week before she died. They never gave up looking. I don’t feel I have to do it – I want to do it. They didn’t get answers. Hopefully I can. If he comes home, the first thing he’ll get is a slap.” She laughs. “All the grief he’s put us through. Then he might just get a hug.”

When someone goes missing, it is usually, understandably, the parents who are forced into the spotlight – the ones who do the police press conferences, the ones who campaign, the people around whom public sympathy gathers. But how does it feel for the brothers or sisters left behind? Often young, they are relatively powerless; they don’t get to decide what happens next, or how the family is going to deal with the trauma. A grieving parent might stifle them with love or worry or both; a grieving parent can shut them out completely. It is common for the sibling of a missing person to feel terrible survivor’s guilt, and to later project their parents’ anxieties on to their own children.

Alex remembers very clearly the night Kevin went missing: her mother looking out the upstairs window all night long; her anger at having to go to school the next morning when Kevin was away, messing about; the fact that only boys could help look for him, in case they found something terrible; the police officer who took her aside and suggested she knew where Kevin was, and that if she told him she wouldn’t get into trouble. They were not allowed to report him missing until he’d been gone 24 hours, because he was 16 and classed as an adult. “Now, all that has changed. As soon as you know someone is missing you can report it.”

By the end of the week, Alex was distraught. Kevin had never run away and had no history of mental illness. “I began to think somebody had taken him. He wouldn’t walk off – that wasn’t him.” The police have never found any trace: nobody saw Kevin that night, there were no CCTV cameras and there have been no reported sightings since.

The family started to receive strange calls. “The first seven or eight months, the phone would ring and there’d be no one on the end of it. Back then, you couldn’t do 1471 or withhold your number. It would ring and ring, then when you picked up, it would be silent. We’d say, ‘Kevin, if that’s you, say something.’ I’d say, ‘Kevin, if you don’t want to come home, meet me at the park after school.’ That was always the time I walked the dog.”

The calls continued for a couple of years. Her mother got them at C&A, where she worked. “She only worked Monday, Tuesday and Wednesday mornings, and that’s when they came.”

Alex became more convinced Kevin was alive after her mother died. At the funeral, she and her father counted the bunches of flowers that had been left. The next day, there was an extra bunch. “I think Kevin put them there. That church was packed. He could have been there, listening.”

His disappearance almost destroyed her relationship with her parents. “They wrapped me in cotton wool. I couldn’t breathe. I wanted to go out, have a life, and I started to kick off. ‘I want to see my friends, this isn’t fair. You can’t keep me like a prisoner.’ I said some hurtful stuff.” Like what? “This is all Kevin’s fault – if he’d just come home, I wouldn’t be treated like this.” At 16 she moved in with a friend. “I couldn’t handle it any more. They were wrapping me up, tighter and tighter.” She and her mother didn’t speak for nearly a year.

The first few months, the phone would ring and there’d be no one there. We'd say, Kevin, if that's you, say something

By 21, she was married with two daughters, who have grown up waiting for uncle Kevin to come home. “They know he was a little sod. He had a magic box and you’d sit down and the whoopee cushion would go. They know so much about him, they want to meet him face-to-face.” Alex segues between present and past tenses.

Does she understand now why her mother became so protective? “Oh God, yeah. If I can’t get hold of my kids on the phone, I’m going ballistic.”

On a good day, she likes to think Kevin joined the military. “Army or navy, on the chefs’ side. I just have that inkling.” The longer you have been away from home, she points out, the harder it becomes to get in touch, even when you want to.

Does a day pass without thinking about Kevin? “No. I work in Sainsbury’s, I could serve him and not realise. I could be at a hospital appointment and he could be sitting next to me. I’m fighting for Kevin to be on Crimewatch, but they can’t do a reconstruction because there’s nothing to show. All they can do is film up the road where he was heading, to the shop that is no longer there.”

I ask why she is so convinced Kevin left of his own accord, and her face collapses. It’s obvious the alternative doesn’t bear thinking about. “Over the years I’ve talked to psychics and mediums,” she says. “A few have said he got taken that night. He got pally with an older guy, racing his remote-control car at Ashburton Park. They say this guy said, ‘I’ve lost the dog, Kevin. Can you help me?’ Kevin was animal mad, so he’d say no problem. Three mediums have said that. Others have said they can taste water, which is a sign of drowning.”

Through the charity Missing People, Alex has met many other families who have gone through similar experiences, and she encourages them to be positive. “When my parents went looking for Kevin, they always looked up, not down. They got pally with the parents of another boy and they were very negative, always looking down under bushes. Mum convinced them to have this little bit of hope. ‘You always have to look up,’ she’d say.”

***

Rachel Elias, whose brother Richard Edwards (known as Richey in Manic Street Preachers) disappeared 20 years ago, aged 27. Photograph: David Barnes for the Guardian

We often come across images of missing people – in the Big Issue, on police station noticeboards, on scraps of paper stuck to trees. And we often assume they are outsiders: addicts or alcoholics, people who have flunked the game of life. But missing people come from all over. An estimated 216,000 people were reported missing in the UK in 2010-11, according to Missing People’s most recent figures, and an estimated 250,000 go missing every year. Home Office statistics reveal that more than half of those are under 18. Most cases are quickly resolved: in 2011, 91% were closed within 48 hours. An estimated 99% are solved within a year. But that still leaves around 2,500 people who go missing every year and leave no trace.

It is 20 years since Richard Edwards’ car was found abandoned near the Severn bridge. Richard, better known as Richey, was a member of Manic Street Preachers, the most tortured and idolised. He was the guitarist who couldn’t play guitar, the skinny boy in eyeliner who cut himself (famously carving 4 REAL into his arm during an interview with NME).

I meet his sister Rachel Elias at her mother’s bungalow in Blackwood, a former mining town in south Wales. Rachel lives down the road, but spends lots of time here with her mother. In a small room off the kitchen, there is a photograph of Richard (Rachel always calls him Richard) receiving his English degree – young, hopeful, not very rock’n’roll. Next to it is a pile of old 45s, some hers, some his – the Smiths, Scott Walker.

Rachel, 45, is a small, striking woman. You don’t need to look hard to see Richard in her. Her memories of him are random, lingering. “One of the last matches he watched on telly was Newcastle v Blackburn. I don’t know why I remember him telling me that. A few weeks before he went missing, our dog died, a Welsh springer spaniel.” They were both living in Cardiff, where Richard had bought a flat. “We came back home, bought a tree from B&Q and buried the dog.”

Richard, two years older than Rachel, was a smart, creative boy, who would help her with her homework. In the years before he went missing, he suffered acute depression; he had only recently come out of the Priory after a previous stay at Whitchurch psychiatric hospital in Cardiff. Rachel didn’t think he was troubled as a teenager, but looking back she can see signs. “He used to pick up a compass and do this.” She scrapes herself with an imaginary compass. “He wouldn’t do it in front of me. But I knew. I never said anything.”

Most cases are quickly resolved: 99% are solved within a year. But that still leaves 2,500 people who leave no trace.

She visited him in hospital and by now he was seriously self-harming. “I’d say, look at your wrists. He’d say, that’s nothing compared to the mental pain I feel. One of the nurses gave him a book by Spike Milligan, Depression And How To Survive It. Milligan said he was so sensitive to things, he felt skinless – I think Richard identified with that.” Did the music business make things worse? “Who knows? Those symptoms might have manifested themselves if he’d been working in a bank.”

She thinks the Priory made him feel special, which she hated – as if his depression was a gift. “You were treated like a pop star. A psychiatrist told my mother he was the Richard Burton of the music world. I thought, what? Because he was Welsh?” Eric Clapton was an occasional counsellor there. “I thought it was funny he and Richard exchanged CDs. He gave him From The Cradle, his blues album. Richard couldn’t even play guitar.”

Richard had told her he wanted to leave the band and just write lyrics for them. But in the end he agreed to a US tour to promote their third album, The Holy Bible. On 31 January 1995, he and band mate James Dean Bradfield checked into the Embassy hotel in London, ahead of their flight. The next morning, when Bradfield knocked on his door, there was no answer. Staff found the room empty except for a few personal items. A fortnight later, Richard’s silver Vauxhall Cavalier was found at the Severn View service station. The Severn bridge was a renowned suicide location – but a lock had been fitted to the steering wheel, which made the family think Richard had been planning to return.

Richard Edwards receiving his English degree

His disappearance was entirely out of character. “He took his responsibilities seriously, and he’d made the decision to return to the band. He used to ring my mum and dad every day, so just deserting them, not making the flight… ”

Rachel knows how many people go missing, but says it’s an isolating experience: “Other people don’t know what to say to you or how to treat you.” Over the years, she has found comfort through Missing People. On her mother’s mantelpiece, there are framed pictures of families. I ask who they are. “Other families with missing people,” Rachel says. “They have become friends.”

There have been numerous conspiracy theories about Richard’s disappearance, including the suggestion he was targeted by government agents because he wrote a song called If White America Told The Truth For One Day Its World Would Fall Apart. But Rachel is not interested in speculation – she just wants the facts. She has campaigned to get the families of missing people one single point of police contact (there were three forces involved in the search for her brother) and has fought for the DNA of missing people to be cross-matched with Britain’s database of more than 1,000 unidentified bodies: “Most people simply don’t know about the database.” It took 10 years to get DNA from Richard’s hairbrush tested. No match was found.

For a while after he went missing, Rachel would drive around at night, looking for him in their old haunts. Then she stopped, thinking it pointless. Twelve years ago, she took a job in a night shelter for homeless people. She never questioned why, then realised she was looking for Richard. “He’d shaved his head and had a bobble hat on before he went missing. And sometimes I’d walk past the living room, see the shape of someone and think…”

She has become less rose-tinted about the world, less secure. “If you go to the Missing People office, there is a wall of grainy photographs. You think you live in a safe world, then you see that and think, no, no. It makes everything seem more sinister.”

Seven years after someone has disappeared, they can be declared dead in absentia. The family decided against this initially, but in 2008, 13 years after Richard went missing, they agreed it would be the best course. Their parents were getting older, and they still had Richard’s bills to pay. His father, who has since died, told Rachel and her mother he didn’t want to leave them with these worries. “So we wound up his financial affairs. Until then we were going down to look after his flat.”

But it was not a simple process. Insurance companies often challenge a case, because they believe families might be on the make. “I had to go in front of the judge and swear on oath that I believe he is dead. That was a very difficult experience. I wrote the affidavit. We had to build up this picture about why we thought he may have died, prove his psychiatric history, how it was out of character, what effort we made to locate him. I’ve met families since who have had multiple applications rejected. Our first was. We had to add more information, then the judge just stamped it.” Can she remember the day they got the certificate? “It just came through. ‘Richard Edwards deceased.’ Yeah, that was hard to read.”

There is still no sense of closure. Does it become easier as the years go by? “Well, recently I’ve come to faith and I go to church. One of the hardest things is that my dad died not knowing. Sometimes I think, well, you have to face the possibility that you may have to live with this uncertainty.” She pauses. “But I think at some point, if not in this life, it will be revealed. And I will know.”

***

Donna Davidson, whose brother Sandy disappeared from his grandmother’s garden 39 years ago, aged four. Photograph: Murdo MacLeod for the Guardian

Donna Davidson imagines the best possible scenario for her brother Sandy. “I’d like to think he was taken by a family who couldn’t have children, and they’ve brought him up well.” She stops abruptly. “But I don’t think that is the case, so I’d prefer he was dead. I’d like to think it happened quick and he didn’t suffer with a paedophile. I definitely think he was abducted and killed.”

It is 39 years since Sandy went missing. He was four and playing in his grandma’s garden in Irvine, Scotland. Donna, who was two, was with him, though she can’t remember it. Despite the picture of the gorgeous little boy with the Shirley Temple locks, she has no memories of him: “That hurts.”

When my youngest was four, he looked just like Sandy. Mum said, cut his curls off. I said, no, you need to get over it

Sandy, aged four

These days she lives by the sea in Saltcoats, Ayrshire. She has three children, recently became a grandmother, and works as a barmaid. Ask anybody, she says, and they’ll tell you she’s the life and soul of the pub. “But it’s all a front. You learn to deal with it. I wouldn’t wish this life on anybody – just not knowing what happened.”

Like so many others, her parents dealt with Sandy’s disappearance by not talking about it. “Nobody mentioned his name. You weren’t allowed to look at pictures.” Her father would disappear on Sandy’s birthday. When she had her own children, the memories came back. “When my youngest boy was four, he looked just like him. And my mum said, get his hair cut off, because he had a mass of curls. He was his double. I said, he’s not getting his hair cut. You need to get over it.”

Did they ever want Sandy declared dead, like Richard Edwards’ family? “No. Even though I think he’s dead, I wouldn’t like that, no. Until we find the body, there’s always that bit of hope.”

Throughout her childhood, her mother worried desperately for her and her younger brother’s safety. Now, Donna says, she’s the same with her own children. “I’ve been overprotective to my kids. The youngest, who’s 15 and Sandy’s spitting image, is a horror. You never know where he is. Whenever my kids go out, my stomach’s in knots.”

***

“I miss the conversations we had. I can’t have those with anyone else. I miss his sense of humour, his music – he had an amazing voice. I miss his face.”

Ben Moore is talking about his brother Tom, who went missing 13 years ago, aged 31. Ben, a curator and film-maker, is seven years younger. We meet in a club in Soho, London, one that began life as a refuge for homeless women in Victorian times. Ben has a bohemian air: well spoken, long hair, chiselled cheeks, slightly tortured demeanour.

When Ben was growing up, Tom was his hero. “I was in awe of him. He liked to play guitar, he had cool friends.” Then he started taking drugs and becoming “weird”. Ben feels guilty: rather than trying to understand, in his early 20s he pushed Tom away. “At that age, all you can think of is trying to tick boxes to be cool, right? And if the boxes aren’t matching, you’re not interested.”

The brothers grew up in a well-to-do family in west London, with another brother and a sister. Their father had been a colonel in the Royal Marines; now both parents teach English. Tom studied theology at Lancaster University, then went to India to find himself, working with the poor and spending time with Mother Teresa (“He wasn’t her right-hand man or anything”). He took mind-altering drugs, and was never the same again. “Give him a drop of anything and he’d twist it into some terrible nightmare. He was religious and there is a lot of fear as well as hope in religion – he got caught up in a paranoid, twisted puzzle.”

Back home, he was put on antidepressants and antipsychotic drugs. “He was on olanzapine, which basically shuts down your mind. Zombie powder. He’d be on it, then come off it, and that’s when it’s dangerous. Suddenly you’re allowed to breathe, you’re awake for three days, and boom!”

Over a period of years, Tom got better. He was never well, but he was calmer. Then one day Mormon evangelists knocked on the door, and he let them in. He became a Mormon, while also embracing his Catholicism. Aged 30, he decided to go travelling again, often to spiritual landmarks and usually without warning. Invariably, there would be a mishap. He was mugged in Paris. He went for a swim in Cannes and somebody stole his clothes. He stowed away on a ship to Corsica, but was discovered and returned to France. His uncle had to rescue him from a hostel in New York.

Missing: Tom Moore. Photograph: missingpeople.org.uk

Ben Moore, whose brother Tom vanished 13 years ago, aged 31. Photograph: Richard Saker for the Guardian

More often, it was Ben who would fetch him. He started to make a film about Tom. Once he disappeared and was discovered in Medjugorje, Bosnia, a site of Christian pilgrimage after local children said they had seen the Virgin Mary. “He was there for a month. I managed to bring him home, but I was questioning why I was. I was only doing it under orders from our parents.”

Ben is convinced his brother is still alive, and is the most optimistic sibling I speak to – because Tom had a history of disappearing. For Ben, it is a case of when, not if. He believes Tom was in Ancona, Italy, on 20 July 2003, because his bank card was used to withdraw a small amount of cash. Since then Tom’s card has not been used, but every few months Ben hears of a potential sighting. He shows me a photo of a man in Italy. He’s red-haired, bearded, craggy, a good Tom lookalike. “What d’you think?” he asks. Well, I say, it does look like him, but lots of people look like Tom. “No,” he says, momentarily deflated, “it’s not him. I’ve got to go with my gut. And when I first saw it, my whole being went, ‘Nah.’ Seeing your brother, it would just be: ‘Boom!’”

Like Rachel Elias, his brother’s disappearance has given him faith. He says he’d like to have his photograph taken in the chapel adjoining the club where we meet. “It has strengthened my faith in Catholicism, and my faith that he’s around.” Ben talks about the day Tom went missing. They were in the middle of a game of chess. “I was winning, and he put it on hold. I wish I’d kept the game. I realise now I was winning because he was distracted by the mission he was about to go on. I realise now he’d come round to say goodbye.”

Tom discovered all these sects when he was travelling. People get swallowed up in them and the years go by

There is a pattern to Tom’s disappearances and Ben takes hope from that. “Tom discovered all these religious cults, sects, when he was travelling. A lot of people within them are registered missing – they get swallowed up and the years go by. He could be with one of them. The only way we’ll see him again is me or someone else finding him.”

Will Tom be pleased to see him? “Yes, it would be such an amazing meeting. I mean, wow! For me, that is the holy grail. It’s as exciting as that.”

He admits he’s as driven by the thought of completing his documentary. He pictures it all – the reconciliation, Tom telling his story. “This is a very selfish, vain part of me talking,” he says, apologetically. “But I’d love to finish that film.”

***

How does it feel for the siblings who come back, or are found? Bill Andrews, 57, had a tough childhood. His mother walked out when he was a little boy, leaving him with his father and an abusive step-mother. He was made a ward of court and spent years in care, frequently running away to search for his mother. As a young man, things started to look up: he worked on the docks and married a woman he loved. But after 13 years she left him. He tried to kill himself, and was sectioned. On his release from hospital, he decided to walk away from everything, leaving Rochester and heading for London. He went missing for 12 years, two of which were spent on the streets. He was eventually helped by the mental health charity Mind to resettle in Dartford, which is where we talk.

The moment you meet Andrews, you know he’s a character – friendly, tough-looking, vulnerable. He wears his cap back to front, is known as Bill the Hat, has Millwall tattoos on both forearms; gold football boots and boxing gloves dangle from his neck. His home is small and crammed with family photographs, especially of his second wife Sharon. He says she saved him.

Eleven years ago, in June 2004, he received a letter from the National Missing Persons Helpline:

“Dear Mr Andrews,

We have been asked by [his mother and sister] to try to contact you. We are able to pass on contact details to you, should you wish to be in touch directly. Alternatively we are prepared to pass on any messages and act as intermediaries.”

How did he feel? “I was shocked. I thought, how the hell did they find me?” It turned out his sister, one of 14 siblings or half-siblings, had moved to Dartford and lived on the same road. She had never seen him, but had heard he had been spotted locally, so got in touch with the helpline.

“For two hours I was walking up and down my flat, pacing and pacing,” Andrews says. “Then I rang them, and they got in touch with my mum. She rang me and said, ‘Come over at the weekend.’ I said, ‘OK. Are you still at the same place?’”

Bill Andrews, who went missing for 12 years. Photograph: Richard Saker for the Guardian

I’m desperate to hear Andrews’ feel-good story – the great emotional reconciliation, how he and his mother caught up on the missing years. But life turns out to be not so obliging. “I’d been missing for 12 years, and at 11.30am she put Sunday dinner on the table. Her famous apple pie and everything. Half eleven, having dinner? I thought, what’s going on? And she shoved me off to bingo. I’d been missing for 12 years and she wanted to go to bingo. Seriously! It was unbelievable.” He hasn’t spoken to his mother for three years, though his relationship with his sister is better.

Sometimes he wishes he was still alone, quietly living his second life. But on the whole he is glad to be reunited, not least because it gives other missing people, and their families, hope. “There are so many people crying out for that helping hand. It’s a shame they can’t show photographs of missing people every day on telly, put out alerts. I do get my bad days…” He stops mid-sentence, and his face lights up. “Then I’ve got my niece ringing up: ‘Bill, when are you coming to see us?’”

He thinks his 12 years missing changed him for the better. Yes, there were terrible times – but if he’d never gone missing he would never have met Sharon. He describes how he walked into a dental surgery when he was at a low. He’d broken a crown, and Sharon was working there. He read her a poem he’d written and 13 weeks later they were married. Then there are all the people he wouldn’t have met if he’d not gone missing. “I started trusting people again. I used to help people if they had nowhere to stay. They called my flat Bill’s Caff. They all used to turn up for biscuits and coffee. I had five or six prams outside.”

What made him start trusting people? “I felt people had gone a long way to help me. Now I could give something back. If I’ve got money, I’ll lend money. I’ll give them food.” This is what gives him most satisfaction. “Helping people get stronger. I learned that on the streets.”

• To contact Missing People, call or text 116 000, or visit missingpeople.org.uk.