Fixing corrupted system files - Windows

A utility by name 'sfc' is available in Windows [XP and later versions] which can be used to restore the corrupted system files.

If any system files [exe/dll/sys/...] get corrupted or infected , the file can be restored with the 'sfc' command.

The help for 'sfc' can be accessed from command prompt.

C:\Documents and Settings\zulfi>sfc /?

Microsoft(R) Windows XP Windows File Checker Version 5.1
(C) 1999-2000 Microsoft Corp. All rights reserved

Scans all protected system files and replaces incorrect versions with correct Mi
crosoft versions.

SFC [/SCANNOW] [/SCANONCE] [/SCANBOOT] [/REVERT] [/PURGECACHE] [/CACHESIZE=x]


/SCANNOW Scans all protected system files immediately.
/SCANONCE Scans all protected system files once at the next boot.
/SCANBOOT Scans all protected system files at every boot.
/REVERT Return scan to default setting.
/PURGECACHE Purges the file cache.
/CACHESIZE=x Sets the file cache size.

To scan and restore corrupted files run 'sfc' from the 'Run' menu as follows.

sfc /scannow

Note: Windows setup disk maybe required.