I am sorry, your encrypted files are gone.
However, if you made any copies of the files and erase them before the event, then those copies might be available in your hard drive memory and USB key memory in an invisible way. I would be happy to point you to some resources that could help you (with no guarantee of results however).
You increase your chance of results at this if you stop writing to your hard drive right now. Put your computer in quarantine until you work the forensics.