How To Fix Windows Defender Security at a Glance | Windows defender not opening problem solved

Here are some ways to fix Windows Defender Security at a Glance and Windows Defender not opening problem:

1. Restart your computer. This is often the simplest solution to many problems.
2. Check if Windows Defender is turned on. Go to Windows Security > Virus & threat protection > Virus & threat protection settings. Make sure that the Real-time protection and Cloud-based protection options are turned on.
3. Check if Windows Defender service is running. Press Windows + R, type services.msc and press Enter. Find the Windows Defender Antivirus Service and make sure that it is started and set to Automatic.
4. Run a virus scan. Go to Windows Security > Virus & threat protection > Scan options. Run a full scan to see if Windows Defender can find any threats.
5. Update Windows. Make sure that your Windows is up to date. Outdated Windows versions may have bugs that can cause problems with Windows Defender.
6. Perform a clean boot. This will start Windows with a minimal set of drivers and programs, which can help you to identify if a third-party program is interfering with Windows Defender. To perform a clean boot, follow these steps:
   • Press Windows + R, type msconfig and press Enter.
   • Click on the Boot tab.
   • Under Selective startup, uncheck the Load startup items checkbox.
   • Under Services, click on Hide all Microsoft services and then click on Disable all.
   • Click on Apply and then OK.
   • Restart your computer.

If you have tried all of the above steps and Windows Defender is still not working, you can try reinstalling Windows Defender. To do this, follow these steps:

1. Press Windows + I to open Settings.
2. Click on Apps > Apps & features.
3. Find Windows Defender Antivirus and click on Uninstall.
4. Follow the on-screen instructions to uninstall Windows Defender.
5. Once Windows Defender is uninstalled, restart your computer.
6. Go to the Microsoft website and download the latest version of Windows Defender.
7. Run the installer and follow the on-screen instructions to reinstall Windows Defender.

If you are still having problems with Windows Defender, you can contact Microsoft support for help. 

I hope this helps!