Windows 10: Unable to start Windows Defender/Security

Hello,I'm unable to open Windows Defender in any way.I've tried:- Right clicking the icon on the taskbar, and clicking "View Security Dashboard"- Starting Windows Security from search- Running SFC No integrity issues found- Running DSIM Completed, didn't solve issue- Changing Windows Security app settings through Apps and Features Settings crashedSecurity is still running in the background, as I've gotten alerts about PUPs. I'm unsure what else to try.Thank you.

:)

 

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 & security center services keep turning off


Are you running any other AV or did you have one running in the past? If you didn't use an uninstaller for the AV, then the remnants of it could be causing the problem. Normally any time you install an AV it disables Defender by default.

If you are getting any error codes please list those, that will be helpful in helping you.

As torre suggested, might be a good idea to do a reset or even a reinstall.

Reset Windows 10 - Windows 10 Forums

Windows 10 - Clean Install - Windows 10 Forums

There are also some suggestions listed here:

Unable to turn on Windows Defender in Windows 7 / 8 / 10

 

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?