I have a windows 7 hp laptop. I want to activate all of windows' good stuff, so I updated immediately after it got a screen repair from the geek squad at best buy. After I am done, I look at the update history and the security updates said to have failed. I tried opening windows defender, but it says application not found. I try to go online and get it, but they just say " you already have windows blah blah blah dont need to install". Please help me install/repair windows defender!

Click Start=>type defender in the search box and look for the program files to ensure they are still on the computer. If Windows Defender is in the program results, click on it to launch the interface. Then select Tools, then options and confirm real-time protection is turned-on as well as the other settings are to your preferences. Your desktop shortcut may be bad if the above worked. Then, Click Start=>type msconfig in the search box=>select it from the programs results=>select the services tab=>scroll down to the w's and find Windows defender in the list. Is there a check in box? If no, select it (check it),=>select Ok=>close out and restart the computer. If yes, it is ok. Cancel and close out. The Geek Squad, really? Support a local entrepreneur IT\computer shop instead, unless it was a warranty job. You can get references.

Sypher2, In case Nano's solution doesn't work: Did you install Microsoft Security Essintinals? If this is the case MSE will disable Windows Defender (because MSE does the same job + Scanning for antiviruses). Else run the system file checker. More info is aviable here: http://www.sevenforums.com/tutorials/1538-sfc-scannow-command-system-file-checker.html Let is know if this solves your problem. Kind Regards DFT IM me - TWiTTer: @DFTER