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How to Scan and Repair Windows Using System File Checker

By Dan Gookin

You can use the powerful System File Checker (SFC) tool in Windows 7 and Windows Vista to ensure the integrity of the Windows operating system, as well as to effectively restore broken parts of Windows without having to completely reinstall the operating system.

SFC may prompt you for the Windows disc, which is either the disc you used to install or upgrade Windows or the system recovery disc provided by your computer manufacturer. Have the disc handy.

When SFC cannot fix the problem, you should try additional recovery options, as described in “Windows Recovery.”

The System File Checker (SFC) is a command line utility in the more recent editions of Windows. Furthermore, you have to start an administrator command prompt to run SFC and have it work its magic.

Before heading into the operation, be aware that running SFC takes time. It’s not a quick-check-before-you-do-something-important type of operation.

Here are the steps to take to scan and repair Windows by using SFC:

  1. Save all your stuff and close any other programs you’re running.

    SFC isn’t a light or casual utility. It does major repair. Don’t blow it by losing information in an open program window. Save now!

  2. From the Start menu, choose All Programs→Accessories.

  3. Right-click the Command Prompt menu item.

  4. From the pop-up menu, choose Run As Administrator.

  5. Click the Yes or Continue button or type the administrator’s password.

    The administrator’s command prompt window appears on the screen.

    You run SFC by typing sfc at the command prompt, but don’t do it yet. After SFC, you can type various options that let it do its magic. The upcoming lists all of them, but the key is /scannow.

  6. Type sfc /scannow and press the Enter key.

    You see text:

    Beginning system scan. This process takes some time.

    Beginning verification phase of system scan.

    Verification 26% complete.

  7. Wait.

    SFC fixes what it can. Mostly, it plods through and displays the results, like this:

    Verification 100% complete.

    What you see after this line depends on the results of the operation. When nothing is wrong, you see this text:

    Windows Resource Protection didn’t find any integrity violations.

    When problems have been found and repaired, you see this:

    Windows Resource Protection found corrupt files and successfully repaired them. Details are included in the CBS.Log windirLogsCBSCBS.log. For example C:WindowsLogsCBSCBS.log

    When things go awry, you see this text message:

    Windows Resource Protection found corrupt files but was unable to fix some of them. Details are included in the CBS.Log windirLogsCBSCBS.log. For example C:WindowsLogsCBSCBS.log

    Don’t fret: Your PC is most likely fine.

    If you’re prompted to insert the Windows disc, do so. Corrupt files must be replaced by fresh ones.

  8. Close the administrator’s command prompt window.

You’ve done the best you can. Hopefully, by running SFC, you have Windows back into shape.

Option What It Does
/offbootdir Specifies the location of boot files when they cannot be found
on the current PC
/offwindir Specifies the location of Windows files when they cannot be
found on the current PC
/scanfile Scans and (optional) repairs or replaces the named file
/scannow Scans all Windows operating system files, repairing or
replacing any that are defective or the wrong version
/verifyfile Scans the named file but doesn’t replace the file
/verifyonly Scans all Windows operating system files but doesn’t
repair or replace any bad files and saves information in a long,
huge log file