Some spyware may create a desktop background to replace your own. After doing this, I’ve seen the display properties tabs for modifying the screensaver and wallpaper disappear to prevent the user from getting rid of the malicious wallpaper. To bring these tabs back, navigate to the following Registry string:
HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionPoliciesSystem
Here, you will find the keys responsible. They are:
NoDispBackgroundPage
NoDispAppearancePage
These will likely be set to 1. Set them to 0 or delete them to get your tabs back.