How to Repair Corrupt or Damaged Windows System Files with System File Checker

How to Repair Corrupt or Damaged Windows System Files with System File Checker

Sometimes one of the important Windows system files can get corrupted. Then you may get messages about missing DLL files or have other indications that there is a problem. This tip will discuss repairing the system with System File Checker (SFC).

This is one of the numerous  command-line system tools that come on all current versions of Windows. It will scan all protected system files and replace incorrect or damaged versions with copies from a backup cache or from an installation disk or folder.

Malware infections are one source of this type of problem so make sure your system is clean before trying repairs. Also, System Restore is easier to use and should be tried first if possible.

Using System File Checker in Windows XP

1.    Open a command prompt (or the Start-Run line).
2.    Type and enter "sfc /scannow" (without quotes but with the space).

Your files will then be scanned and repaired if necessary. It may take 10 or 20 minutes, depending on your system.

Unfortunately, in Windows XP it is quite possible that SFC will first ask for your Windows installation disk. Most people only have a restore disk so it is necessary to take some rather involved steps before running SFC. Even if you have an installation disk, it probably won’t work unless Service Pack 3 is on it. A discussion of how to proceed if you have no proper installation disk is at this Bleeping Computer  forum.  

Using System File Checker in Windows Vista/7 

The procedure generally goes much smoother in the newer versions of Windows. 

1.  Open a command prompt with administrator privileges.
2.  Type and enter "sfc /scannow" (without quotes but with the space). 

Your files will then be scanned and repaired if necessary. Again, it may take 10 or 20 minutes, depending on your system. 

If your Windows Vista/7 system won’t boot, there is still a possible way to try a repair. In such cases, SFC can be run offline using  the Windows Recovery Environment (RE). Again, the catch is that you need a setup disk. Details of using RE can be found at WinHelpOnline .

After running System File Checker

It is best to go to Windows Update after any repair is done to ensure that you have the latest file versions.

As an aside, my personal preference for dealing with corrupt files is regular backups. However, when helping other people (who didn't back up) SFC has its place and is part of the regular toolkit.   

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