Try our best not to write/copy anything on your hard disk that contained your music.
If you have not already checked, see if you can find the files in your Recycle Bin.
If that does not work:
Download Piriform Recuva portable version
on your pen drive or another hard disk from here : http://www.piriform.com/recuva/download/portable
Run Recuva from the pen drive. Cancel the wizard, and scan your hard disk partition on which Windows is installed. You may be able to recover the deleted folder and files.
I hope this works for you.