How to retrieve deleted files from virus

Update windows .Automatically detect and install latest best driver and fix all issues.
Update bios.
Update hdd/ssd firmware.
Full Scan system with "SUPERANTISPYWARE" Freeware.
Then use recovery software.
remember:update antivirus before starting recovery.
recovery softwares recover virus files also so after recovery complete do full scan.

Hi   ,
Don’t get tensed and worry too much about it, just chill. You can surely recover your lost files. some days back even I was in came situation, I just used Flash Drive Recovery Software. It can recover your files very easily and successfully, with ease. It can even recover deleted documents from flash drive even if the flash drive is corrupted.  

For further information about the software, just check out this link:

http://www.recoverdeleteddocument.com/restore-deleted-d...

If you can’t believe it, you try the trial version of this tool and then purchase it. You can download it in this link:

http://www.recoverdeleteddocument.com/download/recoverd...

Just try this, it really works
All the best

Here is a USB drive recovery freeware for you:
http://blog4mark.blogspot.com/2012/12/deleted-files-rec...
This freeware recovered my erased data when my SanDisk flash drive was mistakenly formatted by my little sister. I believe it will help you recover your data from the virus infected drive. Good luck!
Note for you:
1. Do not store any new file on this drive to avoid the original data overwritten by new data, which can make your data gone permanently.
2. Do not save the recovered data on the same drive in case of recovery failure.
3. Do not forget to format this drive to keep it clean.
4. Do not forget to back up your important data as possible as you can in the future.
5. Do not forget to do regular anti-virus scan in the future.