1. Open Start.
  2. Search for gpedit.msc and click the top result to open the Local Group Policy Editor.
  3. Browse the following path:

    Computer Configuration > Administrative Templates > Windows Components > Windows Defender Antivirus

  4. Double-click the Turn off Windows Defender Antivirus policy

  5. Select the Disable option to enable Windows Defender Antivirus.

  6. Click the Apply button.Click the OK button.Restart your device.

If these steps dont turn on the Microsoft AV...the do a RESET of your Windows and start Fresh!

 

Hope this helps!