Synch or swim for Ashlee Simpson. (Craig Robertson, SUN)

There's nothing like screwing up royally on national television to make you grow up really -- make that REALLY --fast.

Just ask 21-year-old pop star Ashlee Simpson, who was caught lip-synching last year during her performance on Saturday Night Live.

"I knew that night it was a big deal," the effervescent Simpson told the Sun in a Toronto hotel yesterday while in town to promote her sophomore effort, I Am Me.

"Right after it happened, I hit the floor and started crying. And I definitely knew, when going to bed. I was like, 'Oh, gosh, what's going to happen tomorrow?' And then I woke up and it was on every news station."

The explanation from Simpson's manager-father Joe was that Ashlee had lost her voice due to acid reflux and didn't want to cancel her SNL appearance, so she used what's called a guide vocal.

But the outrage that followed the incident was staggering.

A website petition demanded a recall of her No. 1 debut album, Autobiography, and she was booed at halftime of the Orange Bowl college football championship.

"I was for sure extremely embarrassed, but I didn't think it was going to be as big a deal as it was," says Simpson, who is very blond again after experimenting with black hair.

"I was, like, 'Okay, everybody messes up, but wow.' It was a really big deal and an (incident) that I don't expect I'll ever live down. But I didn't think 'this is the end of my career.' There was definitely a moment of, 'What's going to happen to me?' "

Simpson says she quickly developed a sense of humour about the incident.

"Quickly, I did. And people would ask me, 'What really happened? What really happened?' And I would say, 'This is what happened.' And they'd be like, 'Oh, she's making excuses.' I'm, like, 'No, it's my fault. I lost my voice. The wrong Pro Tools button was pressed.'"

The whole SNL brouhaha led to Simpson's writing a song about it called Beautifully Broken, which appears on I Am Me.

"It's just about that moment of feeling like you don't want to get out of bed, and then really just beating yourself up and finding your inner strength. I think I learned a lot about myself going through that. Being an adult about it, instead of just being a baby and being sad about it. Really just going, 'Okay, I'm going to face this.' "

Even at her lowest point, Simpson, whose first two albums have been inspired by such '80s rock chicks as Chrissie Hynde, Pat Benatar and Joan Jett, says she didn't feel like packing it in.

"I definitely didn't say I'm not going to do music anymore. I was frustrated but then I was, like, 'Okay, it's all right. Think about somebody like Madonna and how she would have messups in the beginning and everybody hated her or whatever and she kept on going.' And I looked at that and I thought it was cool."

And while record sales of Autobiography may have dipped after the SNL snafu, they eventually bounced back.

"It's something you would never hope or wish would ever happen, but I'm glad that I went through it," says Simpson.

"I think that my fans can relate to me, because who doesn't mess up? And to see somebody actually face it might help somebody with their day-to-day life."

Simpson's recovery got a boost from her second two-song SNL appearance last month for I Am Me, which went off without a hitch.

"It was amazing," she says. "I was ready to go back the day after it happened. I was, like, 'Pul-eeze, give me a second chance!' I got the call. My dad said SNL asked if I'd come back and I was like, 'Absolutely.'

"It felt great going back. I definitely had nerves but it was good nerves."

Simpson says she felt like the audience had her back.

"The crowd was so cute. I was off-air making jokes with them and whatnot. 'Testing, 1-2-3.' Just like silly things and they were so cool. I really felt the support in the room. At the end of the first song I felt great relief and I looked over at my mom and my dad and my friends and everybody was just smiling. Then I walked to my dressing room and everybody from SNL was just like, 'Yeah! You did it!' And so then on the second song I just felt like, 'Ah, I can have fun now.' "

In fact, I Am Me just debuted at No. 1 in the U.S. and No. 4 in Canada.

"It's pretty exciting," says Simpson. "I've had a year of good moments and bad moments and to come out and be on the top with the record was pretty amazing. Surreal, actually. My expectations were definitely not like, 'Okay, number one record,' you know. Nothing like that."

No more reality TV

Ashlee Simpson will sign autographs tonight at Markville Shopping Centre in Markham between 6-7 p.m., an event which is expected to draw at least 1,000 people.

"I have been doing in-store and signings at record stores and stuff, but not in the malls, though," Simpson told the Sun yesterday.

"I really don't get freaked out at all in a situation like that. My fans are really cool and it varies -- their ages --but everybody's always super nice and it's great to see faces and meet people."

Simpson's already begun a club tour in the U.S. for her second album, I Am Me, but doesn't expect to get to Toronto until next year. "I've been doing club tours, which has been a blast and it's really intimate and my fans are there. I've had like a week off and I go back on tour Nov. 10."

Once she wraps up her latest club trek, Simpson plans to go on holidays.

So far, Simpson has no TV or film commitments.

The tabloids have been reporting that she and big sister-singer Jessica -- the only verboten subject yesterday was the subject of Jessica's marriage to Nick Lachey -- might hook up for their own MTV reality series. Ashlee denies this vehemently.

"Absolutely not. I think Jessica and I would probably not have the cameras again like that -- ever!"

The Simpson sisters each had successful MTV reality shows, which are now over.

Simpson also says she wasn't disappointed by the poor reaction to her first film, Undiscovered, which came and went from theatres this summer.

"That film was an independent one and I shot my role in two weeks. It was a blast, and that's something I'd love to continue to do. It was nice to do a film that wasn't my movie and I really enjoyed that, so I think I'm going to more roles like that for a little while and grow as an actress."