(Solved) How To Repair: Windows Defender not Turning on

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Windows Defender (also called Windows Defender Security Center under Windows 10 1703 or later), a fully integrated component of Windows, is an antivirus program. And it provides real-time protection against various threats such as spyware, malware and viruses on your PC. Once it scans and finds potential threats, this program will stop them.

However, many users have reported that their Windows Defender on Windows 10/8/7 cannot be enabled when they try to run this antivirus program by clicking the Power On button.

In addition to the case where Windows Defender was disabled by a group policy, some users said that they did not open Windows Defender with an unexpected error, or that Windows Defender cannot be opened after uninstalling Avast, Bitdefender, McAfee, AVG.

Simply put, this problem can be caused by the installation of third-party antivirus software, a corrupted registry, software conflicts, etc. This is quite common for users of Windows 7, Windows 8 and Windows 10.

What if you have problems because Windows Defender doesn’t work? How can I successfully activate Windows Defender under Windows 8/10/7? Calm down! Calm down! Calm down! Calm down! Get the complete solutions from the next section to help you.

Use specific antivirus removal tools.

If you uninstall third-party antivirus solutions using the Uninstall option in the Control Panel, some files may not be detected, preventing you from running Windows Defender. Read this list of antivirus removal tools and run the tool available for the antivirus program you are using before installing Windows Defender.

In addition to these tools, you can also use uninstaller software to completely remove your antivirus from your PC. If you are not familiar, the uninstaller software is a special application that is optimized to remove programs.

The uninstaller deletes the selected application, but it also deletes all files and registry entries associated with that application. This completely removes the selected application and gives the impression that the application has never been installed.

January 2021 Update:

We now recommend using this tool for your error. Additionally, this tool fixes common computer errors, protects you against file loss, malware, hardware failures and optimizes your PC for maximum performance. You can fix your PC problems quickly and prevent others from happening with this software:

  • Step 1 : Download PC Repair & Optimizer Tool (Windows 10, 8, 7, XP, Vista – Microsoft Gold Certified).
  • Step 2 : Click “Start Scan” to find Windows registry issues that could be causing PC problems.
  • Step 3 : Click “Repair All” to fix all issues.


Restart the Windows Security Center service.

Windows services (also known as.msc services) are used to change the way Windows services work on your system. These services are responsible for running the available programs and managing many system parameters and resources. You can change the settings of a service for security, troubleshooting and performance reasons. You must access Windows services to stop the Security Center service. The Windows Security Center service monitors and reports security status settings on your system. Health settings include firewall, antivirus, anti-spyware, Windows Update and Internet settings. To restart this service, type “run” in Search and click on Run result.

Verify that Windows Defender is running.


In Windows 10, Windows Defender has a small shield icon on the taskbar, although in earlier versions of Windows, you should look for a lock icon.

Look for this icon in the taskbar: it can be hidden in the Options menu, which you can access by clicking on the triangular icon at the top.

If the defender is turned off and your PC is in danger, you will notice that the shield icon has a small cross in the lower right corner. Click on this icon to launch the Defender application and find out if Defender is enabled or disabled.


RECOMMENDED: Click here to troubleshoot Windows errors and optimize system performance