How to Repair Defective or Missing System Files in Windows

1. 1
   Start Windows in Safe Mode with Command Prompt .
2. 2
   Start System File Checker. In Command Prompt, type sfc /scannow and press the ↵ Enter key on your keyboard.
3. 3
   Wait until System File Checker finishes checking and fixing your system.
4. 4
   Shut down your computer by typing shutdown -t 0:00 into Command Prompt and pressing the ↵ Enter key on your keyboard.
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Start the Trusted Installer and Windows Module Installer Services

1. 1
   Open the Start menu. Click the Start button.
2. 2
   Search for Command Prompt. Type cmd.exe .

   • Users of Windows XP must click All Programs then the Accessories subcategory.
3. 3
   Start Command Prompt as an administrator. Right click cmd.exe to open the context menu and click Run as administrator .

   • Users of Windows XP must hold the ⇧ Shift key while right clicking Command Prompt , click Run As to open a dialog window, select the The following user radio button, type Administrator as the user name and the password of the account (usually blank), and click OK .
   • Click Yes on the User Account Control dialog if it appears.
4. 4
   Start the Trusted Installer service. Type net start "trustedinstaller" into Command Prompt and press ↵ Enter .
5. 5
   Start the Windows Modules Installer service. Type net start "windows modules installer" into Command Prompt and press ↵ Enter .
6. 6
   Follow the Steps of Part 1.
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If Starting the Services Does Not Resolve the Error

• Follow the steps of Part 2 to resolve the problem.
• Make sure you aren't attempting to start System File Checker in the 64-bit version of Command Prompt.
  • The title of the Command Prompt window should not say C:\Windows\SysWOW64\cmd.exe .

After System File Checker finishes checking your system for errors, it will present you with a message. The following are the messages and what they mean.

Windows Resource Protection did not find any integrity violations.

• This means that no damaged or missing system files were found.

Windows Resource Protection could not perform the requested operation.

• This means that System File Checker failed to work correctly, but it does not necessarily mean that problems were detected.
• To fix this error:
  • Make sure that folders called PendingDeletes and PendingRenames exist under %WinDir%\WinSxS\Temp .
    • Press the ⊞ Win + R keys simultaneously on your keyboard to open the Run dialog.
    • Type %WinDir%\WinSxS\Temp into the Run dialog and click OK to open Windows Explorer.
    • Search for folders called PendingDeletes and PendingRenames in Windows Explorer.
    • If the folders are missing, copy them into the Windows Explorer window from another computer running the same operating system from the same location.
  • Follow the steps of Part 2.

Windows Resource Protection found corrupt files and successfully repaired them. Details are included in the CBS.Log %WinDir%\Logs\CBS\CBS.log.

• System File Checker found and fixed problematic system files and a log, which is a summary of the repairs made, has been created.
• To view the log (optional):
  • Press the ⊞ Win + R keys simultaneously on your keyboard to open the Run dialog.
  • Type %WinDir%\Logs\CBS\CBS.log into the Run dialog and click OK .
  • The log will be displayed.

Windows Resource Protection found corrupt files but was unable to fix some of them. Details are included in the CBS.Log %WinDir%\Logs\CBS\CBS.log.

• Problematic files were found, but System File Checker failed to repair some of them.
• To fix the files automatically (may not always work):
  • Boot into Safe Mode .
  • Open Command Prompt as an administrator. Click the Start button, type cmd , right click the first search result, then click Run as administrator .
  • Type Dism /Online /Cleanup-Image /RestoreHealth and press ↵ Enter .
• To fix the files manually (advanced):
  • Determine the files that need to be repaired.
    • Open the Start menu. Click the Start button.
    • Click All Programs in the Start menu.
    • Expand the Accessories folder in the Start menu.
    • Start Command Prompt. Click Command Prompt under the Accessories folder.
    • Type findstr /c:"[SR]" %windir%\Logs\CBS\CBS.log >"%userprofile%\Desktop\sfcdetails.txt" into Command Prompt and press the ↵ Enter key on your keyboard.
    • Double click the ' sfcdetails.txt file from your desktop to open Notepad.
    • Navigate through Notepad to look for any corrupted files which System File Checker failed to correct, and note the file names.
  • Find a working version of the file(s).
    • On another computer that is running the same edition of Windows as the computer you are trying to repair, locate the file that was not successfully repaired and copy it onto a removable drive.
    • Search for the file online if it is not available on another computer, and download it from a safe source.
      • Be sure to check the downloads for viruses before using them to repair the computer.
  • Take full control of the corrupted system file on the computer you are trying to repair.
    • On the computer that needs to be repaired, open the Start menu. Click the Start button.
    • Click All Programs in the Start menu.
    • Expand the Accessories folder in the Start menu.
    • Start Command Prompt as an administrator. Right click Command Prompt under the Accessories folder to open the context menu and click Run as administrator .
    • Click Yes on the User Account Control dialog.
    • Type takeown /f "<Path of File>" into Command Prompt and press ↵ Enter on your keyboard.
      • <Path of File> should be replaced with the path of the corrupted file that you want to replace. (E.G. Takeown /f "C:\Windows\System32\notepad.exe" )
    • Type icacls "<Path of File>" /GRANT ADMINISTRATORS:F into Command Prompt and press ↵ Enter on your keyboard.
      • <Path of File> should be replaced with the path of the corrupted file that you want to replace. (E.G. icacls "C:\Windows\System32\notepad.exe" /GRANT ADMINISTRATORS:F )
  • Replace the corrupted file.
    • Open the Start menu. Click the Start button.
    • Click All Programs in the Start menu.
    • Expand the Accessories folder in the Start menu.
    • Start Command Prompt as an administrator. Right click Command Prompt under the Accessories folder to open the context menu and click Run as administrator .
    • Click Yes on the User Account Control dialog.
    • In Command Prompt, type Copy "<Good_File>" "<Bad_File>" and press ↵ Enter on your keyboard.
      • <Good_File> should be replaced with the path of the good copy of the file (depending on where you stored the good version of the problematic file).
      • <Bad_File> should be replaced with the path of the bad version of the file.
      • (E.G. Copy "F:\notepad.exe" "C:\Windows\System32\notepad.exe" )