hmmm... . .I see, my friend had just encountered that same problem. He gave me his USB and here is what I did:
1. Go to "Tools" and click "Folder Option"
2. Choose the View tab
3. Uncheck the "hide protected operating system files (Recomended)"
4. Then click Ok, and then your through.
It works on me. I don't know if it works on you, but probably it will.
I think the virus did something weird on your folders. It is converted into system files, so the
computer will recognize it as a system file, and it has a default of hiding all protected operating
system files. It guess it's like that.
But it's just my thought anyway.