In Windows 8.1, Windows control panel, Windows update and Windows media player will not open, as well as a couple of 3rd party dvd copy programs. Six programs disappeared from Windows start up, including the free antivirus program I have used for years. I ran McAfee Stinger, and the antivirus full system scan and neither found any problems, but since running the full scan the antivirus program will no longer open. I installed several Windows updates a couple of days before this started so I tried to restore to the day before, but system restore does not work either. Ideas and assistance would be greatly appreciated.