Twenty years ago an album that wreaked havoc on the conventional music industry was released. Lauren Spencer, who was among the first to hear Nevermind, reminisces with the surviving band members, and returns to Seattle to hear how Kurt Cobain changed music for ever

Twenty years ago on a hot, smelly mess of an August day, the kind New York City does so well, I crossed the lobby of a swanky hotel in Manhattan to interview a band. They were in town to promote their first major-label release, Nevermind, and because I worked for Spin magazine, I'd been sent an advance of the music. It had caused me to miss my stop on the subway so confused and smitten was I by the soft and hard edges of the tunes and lyrics coming through my headphones. So I was heading up to meet these guys who called themselves Nirvana and find out for myself how they put heaven and hell into each of the songs.

When I stepped into their closet-sized room – twin beds, one chair, one table – I was met by Kurt Cobain, singer- songwriter, guitarist, and David Grohl, the man of drums. Bassist Krist Novoselic had a prior engagement and was not able to join us. That they looked not so much like up-and-coming rock stars as kids whose parents had left them to their own devices – and whose activities may have included bouncing on the beds and making prank phone calls – was heartening, as I was thoroughly sick of the slick interviews I'd been encountering with top-40 rock outfits. Our conversation encompassed homemade tattoos and why Cobain chose the K symbol for his, representing the Washington indie label of the same consonant; that night's free-for-the-fans Metallica party at Madison Square Gardens that they were eager to get into; and how much they loved the trailblazing Sonic Youth.

The fact that within the next few years Nirvana would pave the way for Sonic Youth and other like-minded alternative groups to find a larger audience, as Nevermind toppled pop giant Michael Jackson from his number one spot on the US Billboard charts, was impossible to forecast from this early 90s vantage point, where Bryan Adams's "(Everything I Do) I Do It For You" had been dominating both British and American airwaves for weeks. There was something in this Seattle-based band's songs, live performance and attitude that quickly set the rock 'n' roll industry on its ear, so that what had once been considered an underground sound would emerge to wreak havoc on conventional record chart rankings and traditional music business models.

When I left to go on holiday to Greece the next week, I took Nirvana's music with me. The band imprinted my vacation with incongruities: the clear blue beauty of the Aegean sea and the fuzz-fest mayhem of "Territorial Pissings", a hot shimmering Mediterranean sun infected with the chilling strains of "Polly". It all clashed so beautifully that it woke me up from the Guns N'Roses/Mötley Crüe-like torpor I'd been sunk into of late.

I certainly wasn't alone in responding to that call, as I witnessed on 24 September 1991, the day of Nevermind's release, when I went to Boston to see Nirvana live for the first time. The show was at a club called the Axis, which was apt, since the earth really did seem to shift during their performance. The energy was palpable from the first notes of their cover of the Vaselines's "Jesus Doesn't Want Me for a Sunbeam" and through to their own single "Dive". The notes screamed and bounced off the walls, sweat flew from onstage and off, all combined with incredible melodies while hundreds of kids shook the foundation of the building in their abandon.

There was a sense that the wall separating so-called mainstream music from what was real and raw was being pounded into rubble in front of our eyes by Nirvana's aural celebration and rage. That it all blew completely apart three short years later on 5 April 1994 when Cobain put a shotgun to his head was both inconceivable and, strangely, almost inconsequential, because though both his life and the band came to a tragic and much-too-early end with that trigger pull, Nirvana's legacy had lodged deeply in the public's consciousness and changed music for ever.

In between Nevermind's release and Cobain's death, a diverse and voracious stream of fans and sycophants turned up in Seattle looking for all things grunge, a word that had been given new purpose by the record and fashion industries. They used it to fold into one saleable mass all the varied sounds and stylings of the myriad Pacific Northwest bands, removing it from its original meaning as the stuff that gets underneath your fingernails. No matter what a band's sound, if they came from Seattle, they were categorised as grunge. The term was supposed to describe the lo-fi rumblings and sonic churn of bands such as the Melvins, one of the original groups on the scene that Nirvana admired, yet for every Melvins there was a Posies, a pop outfit whose clear and crystal melodies were anything but muddy. Bassist Dave Fox remembers that when he was on tour with the Posies, "We were always The Posies From the Town of Grunge, but we were so far removed from that scene."

Another of Seattle's nicknames was even more telling. Emerald City was meant to reference the area's surrounding evergreen forests, but it could also have described the tinge of record company currency that had begun to roll in, and the hue of innocence with which the city faced the oncoming masses. "I remember talking about how weird it was that all these [local] bands were getting signed to major labels," says Megan Jasper, vice president of Nirvana's first official label Sub Pop records, describing the aftermath of the 1991 release of Nevermind.

"Suddenly, the clubs didn't feel so empty," she says, "because people were coming in from other parts of the country since they'd heard something was going on here. You'd be walking to a club and someone would pull over and ask, 'How do you get to the Croc-o-dial café?' You'd think, 'Oh, fuck,' because that's where you were going and you didn't know who these people were."

Seattle rock photographer Lance Mercer remembers being amazed when he realised how the scope had changed. "I knew it when Pearl Jam opened for the Red Hot Chili Peppers and Nirvana at the Cow Palace in San Francisco [New Year's Eve, 1991] and I realised two things: one, there was something big going on that I hadn't really noticed; and two, I'd need a much larger lens to capture the action. I had no idea that other people knew Seattle existed. But suddenly I saw the music had all the elements for success. When I first heard 'Smells Like Teen Spirit' on the radio I said, 'Oh man, this is gonna be huge.'"

And the gospel of Nirvana was spreading fast, much more quickly than their record company figured – by using Sonic Youth as their guide they had substantially underestimated how many copies of Nevermind to release. It was clear that the industry would need a new template. Across the country, young people, or at least the young at heart, began to find a muse in their music. Whether Cobain liked it or not – and he frequently made it known how little he did – he was becoming the voice of a generation. Both Nirvana's music and their attitude were beginning to pierce the ultra-slick, airtight container that had up to now held 90s commercial music.

Cobain's often disturbing visual and melodic artistry, mixed with the band members' sense of humour, created a musical model vastly different from the carefully crafted careers the music industry usually constructed with the aid of marketers, stylists and managers. Nirvana were messy. They wore their own clothes and rolled around in their own musical mayhem, giving interviews that often bordered on the absurd, or at least un-checkable, as I found when my researcher attempted to confirm Kurt's last-known address as under a bridge in the logging town of Aberdeen, Washington.

Kurt Cobain and Courtney Love, ‘who could start a war in an empty room’. Steve Pyke/Retna Photograph: Steve Pyke/Retna

Troy Nelson, singer-songwriter, guitarist for Seattle band the Young Evils and DJ at KEXP radio, was a metal-loving teenager in South Dakota when he first encountered Nirvana's music. He couldn't quite make sense of why the band affected him the way it did. "I have a vivid memory of watching MTV and 'Smells Like Teen Spirit' came on," he says. "I was trying to piece together what the hell I was watching. I was completely struck by Cobain's style. They seemed like the stoners next door… like total dorks. But when you're 15 or 16 it felt like they were your friends and they were wreaking havoc. To me Kurt Cobain was the Wizard of Oz. He unveiled the phoniness of so many things. It actually kind of ruined a lot of music for me. But I loved it."

The songs were powerhouses for sure, but the whole package is what counted. "Bands come in and say I want my drums to sound like Dave Grohl's," says producer Butch Vig, who was responsible for the sound of Nevermind. "No matter what I do to this drum kit it's not going to sound like him unless he's the one playing. Maybe that's why there aren't any Nirvana tribute bands – I mean the songs are simple to play, but to pull off their attitude and talent would be hard. It would be easier to pull off a Journey tribute band."

Twenty years almost to the day from when I first entered that New York City hotel on my journey to find Nirvana, I'm standing in another lobby across the country. It's been over a decade and a half since Cobain killed himself and the surviving band members moved on to other projects: Grohl formed the Foo Fighters, Novoselic played bass in the bands Sweet 75, Eyes Adrift and Flipper, and began the non-profit organisation Joint Artists & Music Promotions Political Action Committee. My journey has brought me back to the OK Hotel, a former all-ages club where Nirvana first played "Smells Like Teen Spirit" to a passionate crowd on 8 April 1991. I'm desperate to find something that may smack of the teen spirit that in the early 90s propelled the band into the wider world of music with their raw power, fuck y'all attitude and pop-meets-punk tunes.

But I'm coming up short. I can't find one whiff of the delirious disorder and abandon I used to inhale back in the days when I'd fly out to cover the Seattle scene. There's no sound of music – not even any speakers to pipe it through – no smell of sweat from bodies moving en masse in a too-tiny room. Though the place is practically empty, I'm rooted in the same spot where I'd watched Nirvana, the Fastbacks, Mudhoney and Tad while losing my voice and having my feet stomped on. And now, many years later with Cobain dead and the scene moved on, I find myself instead having an altogether civil and well-modulated conversation about square feet. Because the OK Hotel is now a residential building offering apartments and artist suites, with a gallery planted where the stage and bar used to be.

But there's a perverse sense in this scenario – in light of what transpired, both in Seattle and beyond, in the three years between Nevermind's release and the decorating of the Cobain memorial bench in Viretta Park near the house where he ended his life. Cobain's suicide mummified the band, encasing Nirvana in a layer of nostalgia and removing them from active duty as the agents of change in an industry that seemed to be just opening up to the idea that all shapes and sizes could rock mainstream music. What had made the band so exciting was their attitude, suggesting anyone could experiment in the musical playground and maybe even achieve more than underground success, if that's what they wanted. And it seemed the industry was starting to buy it. But once Cobain was dead, commerce trumped art.

"The thing about Nirvana is that they changed the whole game," says Kurt St Thomas, a DJ at Kroq radio in Los Angeles, who was the first to play Nevermind end-to-end on WFNX in Boston. "Before that album came out there were only a handful of 'alternative' radio stations, and within two years of the record there were more than 100. It should have been a victory, finally good music was getting exposed to more kids who'd never heard stuff like Nirvana, but the radio stations were not really passionate about the music, they were passionate about making a buck, and they started playing Nirvana wanna-bes and watering it down. Once record companies jumped on the bandwagon, it just reeked of business. The image of Spencer Elden [the baby on Nevermind's cover] reaching for that dollar bill is so symbolic to me because that is exactly what it felt like."

After the overindulgence of record companies came the inevitable hangover. Musicians who had been scooped up in the sign-anything-wearing-flannel frenzy found themselves shaken off and having to choose between, as photographer Mercer observed, the blue, the green or the orange apron, signifying a job at either Starbucks, Kinkos or Home Depot.

"So much changed so quickly in the first half of the 90s," says Grohl. "People will tell me how really good that music was, and I agree – a lot of really good music became popular. There was a much more open musical environment and atmosphere. But then it ended up choking itself in a weird way. There were so many bands getting signed from garages and basements from around the country. It was like you left school and had three options: you could either go to college, backpack across the country or start a band and get a record contract – and if it didn't stick, that was when you'd have to go out and get a real job."

Kurt Cobain fronts Nirvana's MTV Unplugged concert in New York City in 1993. Photograph: Frank Micelotta/Getty Images

It seems Nirvana could have only happened then and there; a tight-knit community of local talent had been developing in Seattle for years, out of the spotlight where they had room to grow. Then a perfect storm combining record company budgets with expanding media outlets like MTV hit Seattle's musical shores, dragging more than a few bodies out to sea. Novoselic points out that, "We were the last musical phenomenon before online took hold. In 1999, Napster happened and nothing's been the same since. Now you have to pull people into the music, whereas before everything was pushed out toward the people. The playing field was levelled but now it's so vast that people have to work harder to be heard."

Wandering around the clubs to see what the Seattle kids are up to today, I was happy to find nothing sounded the least like Nirvana. There were the trance-like, Bolly-rock beats of Rose Windows, followed by Wayfinders, who sound like the thick, rich results of Uriah Heep combined with the Smashing Pumpkins. Later I happened upon Troy Nelson's band, the Young Evils, whose harmonies with Mackenzie Mercer are pop gems with an indie beat. Not once during these shows did the word grunge cross my mind. And yet they might not have been heard but for Nirvana. Nelson admits he moved to Seattle because Nirvana put it on the map, "and I'm still to this day trying to write a song as important as 'Smells Like Teen Spirit'."

"I think of it as a forest fire," says Sub Pop's Megan Jasper. "It just felt like everything went up in flames in Seattle so fast, but once it was out, time passed and there was new growth underneath. It makes room for people to come in and do new things. There was something about being in the shadows of grunge and Nirvana. There was a mindfulness because it was so close, and whatever you do, it needs to be different. I think enough time passed that it was OK to emerge and make things happen again. It's respect on one side and rebellion on the other.

"Most people in Seattle don't live in the past," Jasper continues. "Most people are more excited about the here and now. And thank god for that mindset otherwise this place would just be a ghost town." Though if you're into that kind of thing, there is a museum sitting in the shadow of downtown's Space Needle that's dedicated to preserving and sharing Seattle's musical legacy. It's the Experience Music Project, funded by Microsoft co-founder Paul Allen, and right now there's an exhibition running until April 2013 where all things Nirvana are on display. Called Nirvana: Taking Punk to the Masses, it's an ambitious collection of, according to the programme, "rare and unseen artefacts and photography from the band, their crews and families". Larry Reid, punk promoter and manager, says it feels a bit like they've "fetishised" the grunge scene, though, as Novoselic points out, it's better than seeing Cobain's guitar hanging off the wall at a Hard Rock Café while you're eating chilli fries.

I had pangs of déjà-vu as I stared into the glass case that held the sweater Cobain wore for the cover photo that accompanied my story in Spin; but I was heartened to see that one of the main attractions was a dry-erase board where museum-goers could connect any Seattle band, six-degrees-of-separation style, to Nirvana. The board was packed with the names of bands who appeared to be carrying on the very thing I'd imagine Cobain would have wanted if he'd had a chance to choose a legacy. Namely: We're all in this together, let's make some noise.

The Super Deluxe Edition and multi-format reissues to celebrate the

20th Anniversary of Nirvana's Nevermind are scheduled for release on

26 September via Universal Music Enterprises featuring dozens of rare and previously unreleased performances