Windows 10: Unable to start Windows defender

I had installed a third party Antivirus in my Laptop and now its expired and I have already uninstalled it. I am still unable to start my Windows defender.

I tried few steps like Enabling Windows Defender from Group Policy, Deleting conflicting Registry Entry, Restarting Security Center Service as suggested in this link https://answers.microsoft.com/en-us...-windows/808253bb-db89-4db9-a4e5-1c91a86489e9 but nothing works.

When I tried to Enable Windows Defender from Group Policy, it showed this message:



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.

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Moreover this is the message that is shown by Windows security menu:



Please HELP.

:)

 

Windows Defender disabled and is unable to start


OK. I am not sure if you can complete the steps below.......................
In the search box, type services.msc > Enter
Items in the Services box are listed alphabetically.
Scroll down to Windows Defender Service...........................
at Status heading, it should be.................................... Running
at Startup type, it should be......................................... Automatic







If that is not what yours said, right click at Windows Defender Service > click Properties >
can you change the Startup type to Automatic and Service status to Start ?
If yes, do so and click OK when done.

 

Windows Defender disabled and is unable to start


Hi guys!

I finally managed to fix my Windows Defender. I had to restore the service using registry key. And also make changes in the registry using steps mentioned on articles online.

I restored the WD default registry key through the steps provided here this restored my service of Windows defender.

Services - Restore Default Services in Windows 8

It seems that the registry key for WD of Windows 8.1 is same as that of Windows 10.

I also followed the steps mentioned here:
[FIX] Windows Could Not Start The Windows Defender Network Inspection Service On Local Computer

And

Here:

Windows Defender Does Not Start in Windows 10 - WindowsInstructed

So far it's working fine. Will report back if I see anything weird pop up as I did fiddle with the registry keys.

Thanks for the help davidhk

 

Unable to Re-Start Windows Defender Services

A little background first, I downloaded a file and started to install it when Defender caught the virus, but didn't contain it. So I downloaded Malwarebytes to scan and remove the virus.

After I loaded Malwarebytes I noticed I wasn't getting anymore Windows Defender definitions but I noticed the Windows Defender services were stopped and I figured Malwarebytes stopped it and that was the reason I wasn't getting anymore updates on Defender.

I uninstalled Malwarebytes but now I can't restart Windows Defender.

If I got to Control Panel then Security and Maintenance window. Both buttons to turn on Defender are grayed out.





If I search for Windows Defender in the search window on the task bar. This is the result I get.





And lastly, if I go into Task Manager Services, there are 2 entries for Windows Defender, both are stopped. If I try to restart them this is the message I get.





So is there anything I can do to restart the app or does it require more drastic steps such as reload 9926?