1. System File Checker (SFC)

Repairs corrupted or missing system files.

Command:

sfc /scannow

When to use:

• Windows features not working
• Random crashes or missing DLL errors

2. Deployment Imaging and Servicing Management (DISM)

Repairs the Windows system image (often used when SFC cannot fix everything).

Commands:
Check health:

DISM /Online /Cleanup-Image /CheckHealth

Scan health:

DISM /Online /Cleanup-Image /ScanHealth

Repair image:

DISM /Online /Cleanup-Image /RestoreHealth

When to use:

• SFC fails
• Windows Update broken
• System image corruption

3. CHKDSK (Check Disk)

Checks and repairs file system and disk errors.

Command:

chkdsk C: /f /r

When to use:

• Slow performance
• Disk errors
• Blue screen issues

Note: May require a restart.

4. Windows Troubleshooter Commands

Run built‑in troubleshooters quickly.

Examples:
Windows Update troubleshooter:

msdt.exe /id WindowsUpdateDiagnostic

Network troubleshooter:

msdt.exe /id NetworkDiagnosticsNetworkAdapter

5. Network Reset / Repair Commands

Reset Winsock:

netsh winsock reset

Reset TCP/IP:

netsh int ip reset

Flush DNS cache:

ipconfig /flushdns

When to use:

• Internet connectivity issues
• DNS resolution problems
• Network errors after malware removal

6. Boot Repair Commands (in Windows Recovery Environment)

Rebuild Boot Configuration Data:

bootrec /rebuildbcd

Fix Master Boot Record:

bootrec /fixmbr

Fix boot sector:

bootrec /fixboot

When to use:

• Windows won’t boot
• Bootloader errors

7. Reset Windows Update Components

Useful when updates get stuck.

Commands (run one by one):

net stop wuauserv
net stop cryptSvc
net stop bits
net stop msiserver

Then rename update folders:

ren C:\Windows\SoftwareDistribution SoftwareDistribution.old
ren C:\Windows\System32\catroot2 catroot2.old

Restart services:

net start wuauserv
net start cryptSvc
net start bits
net start msiserver