What you mean exactly by "deleted"?
Is it..
a) you delete/ format your usb pendrive?
b) the data in your usb pendrive "automatically"
gone.
If 'b; is the case, you can install malware then run through your PC and your pendrive together. After finish, delete the unnecessary spyware and choose to restart later.
Now you can access the data in your pendrive. Be sure to make a back up. If this happen again some other time, just repeat.
Here's the link to malware..
http://www.malwarebytes.org/mbam.php
Linear Mode
