1. Obtain a command prompt by clicking on the Windows logo button normally at the lower left-hand corner of the screen, then select Programs, Accessories, right-click on Command Prompt and choose "Run as administrator". When prompted for permission to continue, click on the Continue button.
2. At the command prompt, type the command sfc /scannow and hit Enter.

At the conclusion of the scanning process, you will be informed whether any problems were detected.

C:\Windows\system32>sfc/scannow

Beginning system scan.  This process will take some time.

Beginning verification phase of system scan.
Verification 100% complete.

Windows Resource Protection did not find any integrity violations.

C:\Windows\system32>

If there were problems that could not be repaired, you can find information on them by checking the log file produced by the System File Checker tool. The log file is %windir%\Logs\CBS\CBS.log. On most systems, %windir% will be C:\Windows. Typing echo %windir% at a command prompt will show you the directory for the variable. You can open the file in Notepad by typing the command notepad %windir%\Logs\CBS\CBS.log at the command prompt you got by following the steps above.

Or you can use the following steps To determine which files could not be repaired by the System File Checker tool:

1. Obtain a command prompt with administrator privileges as above by right-clicking on Command Prompt, which is found under Programs then Accessories, and choosing "Run as administrator."

2. Then type the command findstr /c:"[SR]" %windir%\Logs\CBS\CBS.log >%userprofile%\Desktop\sfcdetails.txt and hit Enter. That will extract relevant entries from the CBS.log file and place them in the file sfcdetails.txt on the Desktop of the user account you are using when you run the command.

   Microsoft Windows [Version 6.0.6002]
   Copyright (c) 2006 Microsoft Corporation.  All rights reserved.
   
   C:\Windows\system32>
   
   Microsoft Windows [Version 6.0.6002]
   Copyright (c) 2006 Microsoft Corporation.  All rights reserved.
   
   C:\Windows\system32>findstr /c:"[SR]" %windir%\Logs\CBS\CBS.log >%userprofile%\D
   esktop\sfcdetails.txt

Note The Sfcdetails.txt file contains details from every time that the System File Checker tool has been run on the computer. The file includes information about files that were not repaired by the System File Checker tool. Verify the date and time entries to determine the problem files that were found the last time that you ran the System File Checker tool. You can find the file on the Windows desktop or click on the Windows Start button, select Search, then For Files or Folders, then type sfcdetails.txt in the search field to search for the file.

References:

1. How to use the System File Checker tool to troubleshoot missing or corrupted system files on Windows Vista or on Windows 7
   Microsoft Support

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