Windows Defender has turned itself off and can't be turned on

Windows Defender has turned itself off.  I am using the Limited Periodic Scanning option and have moved the slider in settings to turn it back on without success - after exiting Settings and going back in the slider has moved back to the off position. Pressing the Turn on Windows Defender button has no effect - I get an error as follows:

The Service couldn't be started

The specified service does not exist as an installed service

Click Help for more information about this problem

Error Code: 0x80070424

Virus and Spyware definitions are shown as being out of date and can't be updated.

Clicking Help brings me to this forum - not really helpful!

Any ideas anyone?

Charlie Simpson

[Original title: Windows Defender]

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Windows Insider MVP 2017-2020
Microsoft MVP Reconnect 2016
Microsoft MVP Consumer Security 2007-2015
Unified Network of Instructors and Trusted Eliminators (Malware Removal Expert)

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Thanks for your quick response.

I followed the first link but there is no WinDefend key that I can see;

I tried the second link but, again, there is no Windows Defender listed in either the Extended or Standard lists.

As Defender has appeared to be working normally for some time I am at a loss to understand why it has now stopped and also why it is not listed in the Registry or in the Services.

Any further ideas? 

Regards,

Charlie Simpson

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Double check. WinDefend is the service name, Windows Defender Service is the display name.
Windows Insider MVP 2017-2020
Microsoft MVP Reconnect 2016
Microsoft MVP Consumer Security 2007-2015
Unified Network of Instructors and Trusted Eliminators (Malware Removal Expert)

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As you can see there is no occurrence of either WinDefend or Windows Defender in either the Registry or Services. (Apologies for the small image of Services)

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Most likely the Defender Service is missing from the registry or is corrupt. A central repository of Windows services registry exports for Windows 10 can be found here to include WinDefend.reg.

This step involves making changes in the Windows registry. Always Create a New Restore Point in Windows 10 and back up your registry before making any changes.

If that does not fix the service, then refer to these articles.
Windows Insider MVP 2017-2020
Microsoft MVP Reconnect 2016
Microsoft MVP Consumer Security 2007-2015
Unified Network of Instructors and Trusted Eliminators (Malware Removal Expert)

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Ok, found the WinDefend.reg in the list.  What do I do with it?

I have created a restore point but not yet backed up the Registry. (Would the Restore Point not have the same effect?)

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How to Merge Registry Files

It sounds like you do not have experience making registry changes. If you're not familiar with working in the registry, then you should NOT attempt to make any changes on your own. I suggest you get someone to help you. Improper changes to the registry could adversely affect your computer and render it inoperable.

If you make changes on your own, then you do so at your own risk.

Windows Insider MVP 2017-2020
Microsoft MVP Reconnect 2016
Microsoft MVP Consumer Security 2007-2015
Unified Network of Instructors and Trusted Eliminators (Malware Removal Expert)

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What is the Antivirus solution you are using?

You may need to run the AV mfg removal tools and reinstall your AV.

***Pre-installed or user previously installed antivirus may inhibit the current antivirus, use the mfg removal tools to completely remove them, if they were ever on your system.***

Use the mfg removal tools to completely remove them, after running the uninstall in Programs and features see:

https://service.mcafee.com/FAQDocument.aspx?id=TS101331

(MCPR is 1/2 way down the page)

or

Norton Removal tool at:

https://support.norton.com/sp/en/us/home/current/solutions/kb20080710133834EN_EndUserProfile_en_us

For AVG removal see:

http://www.avg.com/us-en/utilities

in addition to the removal tool for your version of AVG.

Use the 'AVG Identity Protection Remover'

List of anti-malware product removal tools

http://answers.microsoft.com/en-us/protect/wiki/mse-protect_start/list-of-anti-malware-product-removal-tools/2bcb53f7-7ab4-4ef9-ab3a-6aebfa322f75

see also:

http://support.eset.com/kb146/?locale=en_US

Reinstall your desired antivirus solution after Windows Defender is updated and working.

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I have Avast! anti virus.  I uninstalled it and then attempted to import WinDefend.reg with the registry.  Unfortunately I got an error stating Error accessing the registry.

I have reinstalled Avast!

Your ideas and suggestions are most appreciated.  Unfortunately Defender is still not working.

Regards,

Charlie Simpson

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With no 3rd party antivirus installed, please try to make the OS (Win10) stable, run sfc/ scannow->

Right click the Start Button->then, left click, Command Prompt (Administrator)-> type sfc/scannow (Hit Enter)

Manually Check your Windows updates (in 'Advanced options' make sure the checkbox is checked to 'Give me updates for other Microsoft products..."

Verify your backup, consider a Win 10 reset (remove everything) or a win10 clean install.. Backup the mfg recovery partition if desired, but do not Factory Restore.

Verify your backup on FileHistory, OneDrive, or some other method you use->

https://answers.microsoft.com/en-us/windows/forum/windows_10-files/how-do-i-automatically-backup-word-docs-onto-the/a0977ed7-e796-405b-be25-fa41441fc4b0

See also;

Reset this PC (Remove everything):

https://support.microsoft.com/en-us/help/12415/windows-10-recovery-options

Win10 Clean install: (have your software and data backup ava for restore)

https://www.microsoft.com/en-au/software-download/windows10

http://answers.microsoft.com/en-us/windows/wiki/windows_10-windows_install/clean-install-windows-10/1c426bdf-79b1-4d42-be93-17378d93e587

https://answers.microsoft.com/en-us/insider/wiki/insider_wintp-insider_install/how-to-perform-a-clean-install-or-reinstall-of/aef0ae63-2117-41ee-a8ea-4a3181625b08

Your antivirus depends on the operating system to be stable, to be effective.

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Last updated January 13, 2019 Views 3,125 Applies to: