There's a program called "Data Rescue X" that will restore deleted files in Mac OSX. That's about the only application I've found that can do it. It's around $50, so you'll have to ask yourself what the file is worth.
Also keep in mind that the more work you do on your computer, the more likely it is the file will get overwritten, so if you're going to restore it, sooner is better than later.
Google is your frenemy.
Caveat Emptor - Latin for tough titty
I tend to interpret things in the way that's most hilarious to me