Many users often resort to reinstalling their Windows computers immediately for being unable to fix an error. To them, some computer problems are impossible to troubleshoot that starting over seems like the best and only solution. But reinstalling Windows is a hassle; you have to reconfigure settings and reinstall your favorite programs. It should only be your last option, because Windows has several utilities for fixing problems. When it comes to corrupt Windows system files, your best bet is the System File Checker.
Starting in Windows Vista, the System File Checker is built into the Windows Resource Protection (WRP), which safeguards registry keys, folders and essential system files. If it discovers that changes have been made to these entities, WRP reverts the changes by obtaining clean, cached copies from the system backup folder that came with the operating system.
What Causes Windows System Files to Become Corrupt?
A variety of events and user activities can cause Windows system files to become corrupt. Those tweaks you performed carelessly that modified critical keys in the Windows registry, accidental deletion or overwriting of critical files, badly developed programs, and malware—all of these can corrupt Windows system files. When corrupt files exist, Windows may not work as intended. It may even crash.
How to Run the System File Checker
The entire process requires time and CPU resources. It’s best that you don’t do anything else while running the utility.
In order to run the System File Checker, you first must need to open an elevated command prompt (i.e., running a command prompt as an administrator). Press Start, type cmd in the search field, right-click the Command Prompt when it appears in the search results and select Run as administrator. Enter the username and password of an administrator account if asked, or click Allow.
In the elevated command prompt, type sfc /scannow and press Enter. The System File Checker immediately begins with its system scan and automatically attempts to repair or replace any corrupt files it finds. The whole process may take a while to finish, and you may be asked to insert your Windows installer disc.
Note: If, upon entering the command, you receive a “Windows Resource Protection Could Not Start the Repair Service” error message, press Windows+R, type services.msc and press Enter. In the Services window, scroll down to find the Windows Modules Installer service. Right-click it and select Start. Try running the SFC utility again.
Note: If you know which specific system file has become corrupt, you can use the command sfc /scanfile instead. Or if you just want the utility to scan the system without making automatic repairs, use sfc /verifyonly. You can view all available commands by typing sfc /? in the command prompt.
Wait for the SFC utility to finish. When it’s done, it may show one of the following results:
Windows Resource Protection did not find any integrity violations.
In other words, your computer has no corrupt system files. The issues you’re currently experiencing must have other causes.
Windows Resource Protection could not perform the requested operation.
Something is preventing the utility to run or make repairs. In this case, try using the SFC utility in safe mode.
Verify that the folders Pending Deletes and Pending Renames are still present in %WinDir%\WinSxS\Temp. To go there, copy-paste that address to the address bar in Windows Explorer.
Windows Resource Protection found corrupt files and successfully repaired them.
This means you were right to suspect your computer of having corrupt files. Fortunately, the utility has managed to repair them all. All you need to do at this point is to restart your computer to let SFC finish any remaining repair operations.
Windows Resource Protection found corrupt files but was unable to fix some of them.
The utility has encountered a more serious problem that it couldn’t fix by itself. You need to step in and perform the repairs manually.