Hollywood has never been kind to its young. It is an industry that famously venerates youth and, infamously, has casually destroyed so many young people, used them up then discarded them, that to list them all would fill this entire article. The film business loves to look at young people, but has less than zero interest in looking after them. Some are destroyed over a long period, such as Judy Garland, some barely have time to draw breath, such as River Phoenix. And then are the other less sensational but no less instructive stories of the young people whose hopes were raised by the industry, but find themselves whimsically discarded.

At the start of this century, Thora Birch was one of Hollywood's most credible young actors. She transitioned nicely from cute kid actor (as Harrison Ford's daughter in 1994's Clear and Present Danger) to interesting child star (in 1999's American Beauty) to delightful indie darling (2001's Ghost World). Then she disappeared, and no one seemed to know where or why.

Last week, I found her in the incongruous setting of a grimly formal restaurant in west Hollywood, where tablefuls of seventysomethings ordered fillet steak while, outside, LA was baking hot. Waiting for me in the entrance, Birch looked utterly unchanged, in layers of dark clothes, with mussed hair and smears of blue eyeshadow across her lids.

"It's been a while since I talked to anyone as cool as the Guardian," she says as we sit down, with an emphasis that shifts uncertainly between irony and self-deprecation. This statement seems ridiculous (on multiple levels). In 2001, Birch was nominated for a best actress Golden Globe. We happen to meet two days after this year's Golden Globes and she is, she mutters at one point, "currently looking for an agent". How this happened is not straightforward and it is not really clear if Birch understands it herself, or how she feels about it. Contradictions pepper her conversation. Initially, she talks about how she "decided to take a break and live my life, branch out a little, educate myself". But when I make the mistake of suggesting she "stepped back", she snaps: "It makes me angry when you use that phrase because I didn't step back. I was always working, it's just that no one was paying attention." At times, she has the dazed but anxious air of someone who has just emerged from a long sleep and is astonished at how much time has passed.

Thora Birch (right) with Scarlett Johansson in the 2001 film Ghost World.

In her heyday, Birch was a lovely, natural presence on screen, the foil to her glamour-puss contemporaries, such as Mena Suvari (who also, less surprisingly, faded away) and Scarlett Johansson (who did not). She often seemed pleasingly detached from the Hollywood fluff machine, making a begrudging smile on the red carpet.

"I tried to walk a fine line between being alluring and somewhat glamorous but maintain a strong identity and pursue things that were a little more thoughtful, and I guess nobody really wanted women to do that at that time," she says.

Did she feel people were trying to make her into something she wasn't? "I just felt like I was making people angry, because I wouldn't wear the frilly bows. I just didn't take advice and I think people got pissed off at me for not taking advice."

Did she struggle with the glamour that her industry demanded of her as she transitioned from being a child star? She pauses for a full minute. "I struggled with reconciling that there was a reason for all that. I found it distasteful. So yeah, I had that kind of 'oh, piss off, everyone' attitude."

In the late 90s and 2000 the cool young female actors on screen were pretty, but in a grungy, even self-effacing way, and they looked as if they would rather eat their ankle-length skirts than have a blow dry: Juliette Lewis, Julia Stiles, Leelee Sobieski, Winona Ryder. As Birch grew from child to adult actor, she fitted into this trend perfectly. But by the early noughties, a very different look was emerging for young female celebrities, one based more on Paris Hilton than Kurt Cobain. You only have to look at Ghost World to see what options were available to young women in Hollywood at the time: they could glam up and be A-list sex symbols, like Johansson, or they could refuse to wear the frilly bows and disappear, like Birch.

How does it feel when she looks at Johansson's career, considering she accepted all the things Birch rejected?

Birch screws up her face: "I don't know. Look at her. Whatever," she says in a "like duh" tone. "I still love her, we were kids together …"

Another factor in Birch's disillusion with Hollywood was that she was a witness to its casualties, having worked with Brittany Murphy and Brad Renfro.

"I'd seen Brittany here and there before and thought she was cute and lovely and all that stuff. But when I worked with her I saw the condition" – she twirls her finger next to her head – "and I thought, that can't be good."

As for poor Renfro, who died at 25 from a heroin overdose in 2008, Birch says she was "shattered by the state of him" when they made Ghost World: "I wish I'd said something, like: isn't there something that should be done, other than a guardian who is not a guardian …" In neither case, she says, was she surprised when she heard about Murphy and Renfro's deaths "and that was another problem for me".

Thora Birch with Wes Bentley in the 1999 film American Beauty. Photograph: Sportsphoto/Allstar/Cinetext Collection

Birch was born and brought up in Los Angeles, just a few blocks from where we meet. She started acting in adverts when she was four, and loved it, despite her parents' wariness. They themselves had worked in porn films, including Deep Throat, but a question about whether their experience in the film industry made them anxious for her causes Birch's internal shutters to slam protectively down: "I don't know. I refuse to talk to them about any of that."

They named their daughter after Thor the Norse god (and their son Bolt, presumably after lightning), and it is a good name for her: Birch is not afraid of roaring. She has, she agrees, always been "mouthy", by which she means she is engaged and vocal. When she talks about the way legislation works in America, she nearly cries with frustration, and her blog is full of passionate outrage over current events. But this sense of engagement has not always made her easy to work with: when she was just 14, she was fired from the Alexander Payne film Election because "I read the script one way and it became clear that [Payne] had seen something else, so that was it. I just thought, this is ridiculous: why is it written this way?"

In 2010, she was fired from the off-Broadway theatrical revival of Dracula after it was alleged that Birch's father, Jack, her manager and a frequent presence at his daughter's rehearsals, had physically threatened one of the other actors. Birch said at the time that she was "in a state of shock". When I ask Birch about it now, she looks down in silence. Then she says: "I pissed a lot of people off over a long period of time and they found a way to upset me, hoping that upset would bring a change in my behaviour. Like a distancing … But I'm done, I'm done. People wanted me to be not fine. A lot of it was bullshit."

Has she felt that for a long time that people are trying to get her, that they're angry with her?

"Yeah, definitely."

Why are they angry?

"Because I should just shut up."

Because she's a young woman? Because she's an actor?

"All of it."

Talking with Birch is a little like trying to stand one's ground during a minor earth tremor: just when I think I've found my footing, her rhythm changes as she switches between bolshy self-confidence and nervy insecurity. Her tone can alter from thoughtful to defensive aggression to sarcastic sing-song in the space of a few minutes. But the overall effect is of a person who has been somewhat battered by setbacks and feels the need more than ever to prove herself. She is right: she never stopped working, but in things that never flew. Since Ghost World she has made several TV movies, the John Sayles film Silver City, which could have been successful, and produced a film, Petunia, "which got in, like, two cinemas". The truth is, what happened to Thora Birch was a bit of bad timing, a bit of bad luck and the accruing of a bit of a bad reputation. Ultimately, she just stopped fitting in. But considering how weary she is of the industry's foibles, it surprises me that she is keen to get back into it: currently trying to get a screenplay produced and to work again in films "people actually watch".

Does she feel bruised from past experiences? "No, more from the present state. Because I'm not going to sit here and act like everything's glorious and wonderful." She pauses, changes her mind and then leans closer to me and says more insistently: "Even though I do kinda feel like that. Like with my life? I'm really lucky! I'm just cognisant that I wanna move forward, and people will let me or not, who knows."