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.

Startup Repair is a Windows recovery tool that can fix certain system problems that might prevent Windows from starting. It scans your computer for the problem and then tries to fix it so your computer can start correctly.

The Program Install and Uninstall troubleshooter helps you automatically repair issues when you're blocked from installing or removing programs. It also fixes corrupted registry keys. 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.

If you are having issues installing or updating Gaming Services on your PC, or if you are noticing that the Xbox app for PC is launching with missing content, you may want to download and run the Gaming Services Repair Tool for PC.

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.

Running Windows Update Standalone Installer (wusa.exe) with the /uninstall switch on the combined package will not work because the combined package contains the SSU.

Windows Recovery Environment (Windows RE) is a set of tools included with Windows that can help you troubleshoot and fix common problems with your computer. If your PC is having trouble starting up, Windows RE can automatically start and try to repair the issue. Windows RE is also a starting point for various tools for manual system recovery.

To verify if you have WinRE enabled, run the following command in an elevated command prompt: reagentc /info. If WinRE is enabled, you will see Windows RE status in the output with a value of Enabled. In this scenario, this update might be needed.

AC-3 is an audio codec that supports multi-channel (“surround sound”) audio. It's also known as Dolby Digital. On versions of Windows prior to Windows 11, version 24H2, the AC-3 codec is included. Beginning with Windows 11, version 24H2, the AC-3 codec is no longer included with Windows.

For the most complete scan, run Microsoft Defender Offline. For more about that see Help protect my PC with Microsoft Defender Offline. When the scan completes, Defender will tell you if it found anything. When would I want to run a scan?