How to fix Windows Defender not running in Windows 11? Turn on Windows Security Head to the Start menu search bar, type in 'security,' and select the best match.From there, click on Turn on to enable the Virus & threat protection of your PC. A new dialog box will pop up asking you to confirm if you want to confirm the changes; click on Yes to go ahead. The Windows Security will be enabled instantly. Update Windows 11 To check for updates, launch the Windows Settings. Go to the Start menu search bar, type in ‘settings,’ and select the Best match. Alternatively, press Win + I together. Scroll down and select Windows Update. Now click on Check for updates and Windows will start checking for updates on your PC. If any new updates are available, they’ll be displayed on the Windows Update screen. All you have to do is click on Download & install to get the ball rolling. When the updates are complete, give your PC a quick restart and see if the problem with Windows Security persists. If it does, then jump below to the next method. Disable/Uninstall Third-party Antivirus To get started, launch the Settings again. Go to Apps > Apps & features, search for the antivirus, and when you find it, click on options (three dots) and select Uninstall. However considering you have already purchased Restoro and would like us to assist you in doing that utilizing a remote session, please contact our support and they will be happy to help you. Email: support@restoro.com