How to Check the Integrity of the Windows 7 System Files

Windows  includes a  utility that  scans your  Windows 7 system for corrupt, changed  or missing  system files. Normally  you run  this utility in booting  off the DVD into repair mode but running this from the command prompt is much easier.To run this utility , you will need to open a command prompt in administrator mode and follow the  steps.

1. Go to Start menu.
2. Select All Programs and then Accessories
3. Right-click on Command Prompt and select Run As Administrator.You can run the service in Command Prompt, by using the following syntax: SFC [/SCANNOW] [/VERIFYONLY] [/SCANFILE=] [/VERIFYFILE=] [/OFFWINDIR= /OFFBOOTDIR=]
4. Press Enter

This  will scan and attempt to repair any files that are changed or corrupted. You can run that command with sfc /scannow.