Cannot turn Microsoft Defender back on after uninstalling third-party antivirus

Question

Hello, I've been using Bitdefender Free for years and I wanted to start using Microsoft Defender (MD), because I've recently heard that it works very well. I knew MD is deactivated when another antivirus is installed and is supposed to activate on its own as soon as no other antivirus is active.

I uninstalled Bitdefender (through 'Control Panel'>'Uninstall or change a program') and Windows Security (WS) warned me that I was no longer protected.

When I go to 'WS'>'Virus and threat protection' I'm warned that my device is vulnerable.

If I go to 'Security providers' this is what I see:

And if I click on that, nothing appears in the menu:

I've tried going to 'Services' and starting 'Microsoft Defender Antivirus Services', and was returned this (same with 'Microsoft Defender Antivirus Network Inspection Service'):

I have run the System File Checker as an administrator and it found no issues.

I have also checked my WMI repository and it is deemed consistent.

I have restarted my computer multiple times.

I have tried restarting 'Services'>'Security Center', but the 'Restart' option is greyed out:

I've tried accessing the 'Group Policy Editor', but 'Run' cannot find it, apparently:

I've tried every solution I've found online. Solving problems on Windows is so frustrating.

Answer 1

Good Day A Molle Targate,

My name is Carlo, I am also using Windows 10 pc and community member like you. Let us work together to sort this out.

Here's the steps you can try.

-Click Start, type CMD and run as administrator

-Copy and paste each of the command below and hit enter.

reg delete "HKCU\Software\Microsoft\Windows\CurrentVersion\Policies" /f

reg delete "HKCU\Software\Microsoft\WindowsSelfHost" /f

reg delete "HKCU\Software\Policies" /f

reg delete "HKLM\Software\Microsoft\Policies" /f

reg delete "HKLM\Software\Microsoft\Windows\CurrentVersion\Policies" /f

reg delete "HKLM\Software\Microsoft\Windows\CurrentVersion\WindowsStore\WindowsUpdate" /f

reg delete "HKLM\Software\Microsoft\WindowsSelfHost" /f

reg delete "HKLM\Software\Policies" /f

reg delete "HKLM\Software\WOW6432Node\Microsoft\Policies" /f

reg delete "HKLM\Software\WOW6432Node\Microsoft\Windows\CurrentVersion\Policies" /f

reg delete "HKLM\Software\WOW6432Node\Microsoft\Windows\CurrentVersion\WindowsStore\WindowsUpdate" /f

Add-AppxPackage -Register -DisableDevelopmentMode "C:\Windows\SystemApps\Microsoft.Windows.SecHealthUI_cw5n1h2txyewy\AppXManifest.xml"

If you getting errors when you enter each of the commands , it fine that's normal, just proceed with the next command.

Once you entered all those commands restart your computer and check the Windows Defender.

If issue persists proceed with these steps.

-Press Win+R to bring up the Run dialog box. Type ‘regedit’ and run it as administrator

.

-Navigate to: HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender

-Right click on Windows Defender, over the mouse to New and click on DWORD

-Double click on newly created DWORD called DisableAntiSpyware, set the value to 0 to Enable Windows Defender.

Restart once done and check the Windows Security .

I hope the information above helps. Please let me know how it goes.

Have a wonderful day ahead and stay safe.

Sincerely,

Carlo T.

Answer 2

Your first solution solved my problem, thank you so much! I wish I knew what I have done, but I'm fine with having achieved the desired result.

I wish you a great day as well!