OK, listen carefully!
STOP USING THAT DRIVE RIGHT NOW! DO NOT WRITE TO IT OR ANYTHING!
We don't want to risk writing over the data. Now, you just need a data recovery software. Here is a good one that is pretty reputable. It is called Recuva.http://pcsupport.about.com/od/filerecovery/gr/recuva-review.htm
Download and install that and give it a whirl. But do not write or do anything to the drive until then.