apply last backup and roll logs forward until point in time / last log backup.
Failing that you may be able to recover using a log explorer type program, which you'll probably have to buy as most don't allow evals to work on user databases, for obvious reasons. This method is more painful!
[font="Comic Sans MS"]The GrumpyOldDBA[/font]
www.grumpyolddba.co.uk
http://sqlblogcasts.com/blogs/grumpyolddba/