Windows Defender Application Not Found Windows 7 Link -

Try launching Windows Defender again.

Press the Windows Key + R on your keyboard to open the Run dialog. Type services.msc and hit Enter. Scroll down the list until you find Windows Defender. Right-click it and select Properties. Set the Startup type to Automatic. If the Service status says Stopped, click the Start button. Click Apply and OK, then restart your computer. Re-register Windows Defender Files windows defender application not found windows 7

If SFC finds corrupt files, it will attempt to replace them with cached copies. Restart your computer and check if Windows Defender works. Try launching Windows Defender again