Such problem occurs when you are affected by a w32.USBworm or its varient. Although now there are updates to clean this worm but still you are not able to unhide hidden folders. In such case one of the following registry edits work for sure.
Solution 1:
Go to Start –> Run, then type regedit and press Enter
Navigate to
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\
CurrentVersion\Explorer\Advanced\Folder\Hidden\SHOWALL
Find a key called CheckedValue
Double Click “CheckedValue” key and modify it to “1“. This is to show all the hidden files.