Remember Me? by Sophie Kinsella

The popular author Sophie Kinsella (of Shopaholic fame) introduces a new heroine with a big problem. Lexi Smart wakes up in the hospital with a case of amnesia caused by a head injury. The last thing she remembers is being a loser: crooked teeth, frizzy hair, no money and a dead-end job. But apparently the three years she can't remember were big ones: she's now sleek, sophisticated, rich, a successful businesswoman and married. But as she tries to reconstruct her recent history, Lexi begins to dislike the woman she became. If you're a fan of Samantha Who? or are just in the mood for a funny and touching story, this is the book for you.