Enable the Hidden files and folders option:

Most viruses hide themselves as soon as they're executed. But when they're later removed by the anti-virus, you'll find that the Hidden options in the Folder options menu wouldn't work. This is caused by the virus but even if it is deleted, some of the changes done to the system by the virus remain unchanged. This can be solved by using the following methods

1. Go to Start --> Run and type "regedit".
2. Navigate to the following key
   
   HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
   


3. On the right-hand side, look for the key with the name "hidden" and set its value to 1. 
4. Thats it. You're done. 
5. If the above try dint work, navigate to the following key
   
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Folder\Hidden\SHOWALL
   


6. Now search for the “CheckedValue” DWord key on the right-hand side and make sure the hexadecimal value is set to 1.


7. Now go to your folder options and enjoy hiding your secret files and folders.