|no, it doesn't seem like a virus.|
personally i think you've been putting music on then taking the mp3 usb out...you have to use safely remove hardware tool before disconnecting with windows otherwise the device becomes currupted...
same with all usb drive/devices
yes it doesnt always currupt the device if you dont use the tool but its 50/50
and no, there is no recovery is this is the problem..sorry,
hopefully i'm wrong and you will find an answer soon
all the best