Sometimes, in very rare cases, Windows Defender is grayed out/disabled instead of showing a connected status. To solve it, update your Windows system first, which might clear the problem automatically. If it doesn't, go back to the Windows Defender key in Registry Editor and check for a "Disable anti-spyware" parameter; it may not be present if your system is running properly. Right-click on it. You will get an option to "Modify," which will take you to a screen where the "DWord" value is to be changed from "1" to "0." Once you do this modification, you should be able to access Windows Defender once again.