Check out an article at Lifehacker: “How to recover deleted files with free software”
Ack! The computer ate my term paper! We’ve all been there at some point. You delete an important file, somehow it skips your Recycle Bin altogether, and for all practical purposes, it’s disappeared into the ether. But before you hit the big red panic button, there’s a very good chance that your file is still alive and kicking somewhere on your hard drive—you just need to know how to find it. With the right tools, finding and recovering that deleted file can be as simple as a few clicks of your mouse.