We all have misbehaved deleting an innocent looking file just to discover after a while that we don't have any copies left and we need it badly. For this common error, I can recommend you this software called Recuva, wich will recover all your files if you don't wait too much for trying.

This is possible because most operative systems do not actually erase the files, but just delete them from the list of contents of the disk, marking their space as avaliable for other programs to write in.

The app is very intuitive, just remember not to install it at the disk where you're going to try to undelete the files. You'd better decompress the portable version into some flash drive or alike, and run it from there.