How to Enable or Start Windows Defender manually in Windows 10

If you have installed a 3rd-party antivirus software, Windows Defender will turn itself off, automatically. When you uninstall your antivirus software, then on restart, Windows Defender will turn on automatically and protect your Windows PC. But if you find that it does not, then you will have to start Windows Defender manually. This post will show you how to enable or start Windows Defender manually on a Windows 10/8/7 computer.

Start Windows Defender manually

To start Windows Defender, you have to open the Control panel and Windows Defender Settings and click on Turn On, and ensure that the following are enabled and set to On position:

  1. Real-time protection
  2. Cloud-based protection.

We have already seen how to disable Windows Defender now let us see how to enable it.

When there is no security software protecting your computer, you will see notifications like these appear.

Enable or Start Windows Defender

Clicking on it will show you the installed security apps on your system. If you miss this notification, you can see it in the Notification & Action Center.

Enable or Start Windows Defender

Clicking on it too will show you the installed security apps on your computer, as follows.

Enable or Start Windows Defender 5

Select Windows Defender and then click on the Turn on button.

Windows Defender will start. The first think you want to do when this happens, is to update your definitions.

Start Windows Defender manually

Clicking on the Settings link in the top right corner will open the following panel. You can also access it via Settings > Update & security > Windows Defender.

windows defender settings

Once here, ensure that Real-time protection and Cloud-based protection is set to On. You may also set Automatic sample submission to the On position. You may then configure Windows Defender according to your needs.

Windows 8 and Windows 7 users can search for ‘Windows Defender’ via the Start Search and do the needful.

If Windows Defender will not turn on, you may need to check on the status of its Services and components:

  1. Unable to turn on Windows Defender
  2. Windows Defender will not turn off even when 3rd party AntiVirus is installed
  3. Windows Defender is turned off or not working.
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Anand Khanse is the Admin of, a 10-year Microsoft MVP Awardee in Windows (2006-16) & a Windows Insider MVP. Please read the entire post & the comments first, create a System Restore Point before making any changes to your system & be careful about any 3rd-party offers while installing freeware.