What to do if all windows icons have been changed to shortcut LNK files and we are not able to open any program?

Ans:.1. Click on Start > Run > type "regedit" and press the Enter 
        2. Navigate to HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.lnk\ .
        3. Delete user choice folder, close registry editor and restart your machine.

Hope this will help to resolve issue..