Use the System File Checker tool to repair missing or corrupted system ...
When critical Windows system files are missing or corrupted, some Windows features may stop working correctly or Windows may stop responding altogether. If this happens, you can use the Deployment Image Servicing and Management tool (DISM) and the System File Checker tool (SFC) to scan your system files and restore any corrupted or missing files.
Uninstall or remove apps and programs in Windows - Microsoft Support
There are different ways to remove apps and programs, so if you can't find the one you're looking for, you can try another location. Note that some apps and programs are built into Windows and can't be uninstalled. You can try to repair a program first, if it's just not running correctly.
Fix problems that block programs from being installed or removed
First, you'll need to download the troubleshooter. Download troubleshooter. If you see the File Download box when you start downloading, select Run or Open. The troubleshooter provides steps for you to follow. If a program isn't listed in the uninstall options, you'll be asked for that program's product code.
Automatically fix Windows security issues - Microsoft Support
Follow these steps to automatically diagnose and repair Windows security problems by turning on UAC, DEP protection, Windows Firewall, and other Windows security options and features. Select the Download button on this page. In the File Download dialog box, click Run or Open, and then follow the steps in the Windows Security Troubleshooter. Notes:
Using System File Checker in Windows - Microsoft Support
System File Checker is a utility in Windows that checks for problems with files on your computer. To run it, follow these steps: Make sure you've installed the latest updates for Windows, and then restart your machine. To find out more, read Update Windows.
How to start a scan for viruses or malware in Microsoft Defender
For the most complete scan, run Microsoft Defender Offline. For more about that see Help protect my PC with Microsoft Defender Offline. Select the type of scan you want to run, then Start scan. When the scan completes, Defender will tell you if it found anything. When would I want to run a scan?
Applies To: Microsoft Defender on Android, Microsoft Defender on Mac, Microsoft Defender on Windows
Windows troubleshooters - Microsoft Support
Get Help has troubleshooters you can run for many common scenarios. These often help resolve issues without the need to contact support. If a troubleshooter is available for your issue, select Run to start that troubleshooter.
Fix problems that block programs from being installed or removed
First, you'll need to download the troubleshooter. Download troubleshooter. If you see the File Download box when you start downloading, select Run or Open. The troubleshooter provides steps for you to follow. If a program isn't listed in the uninstall options, you'll be asked for that program's product code.
Repair apps and programs in Windows - Microsoft Support
You can repair some apps and programs if they're not running correctly. Note that you won't see repair, change, or modify options for all apps and programs. Repair options from the Settings page. Select Start > Settings > Apps > Installed apps. Select the More icon next to the app you want to fix.
Windows Security Update - Microsoft Support
This update provides latest updates for Windows Security platform, which is comprised of the Windows Security app and its underlying service. To obtain the current version of Windows Security app, please run powershell command below: Get-AppPackage Microsoft.SecHealthUI. Manually download the update. 64-Bit | ARM64.