How to to scan and fix corrupted or missing 

Windows system files. 

1. To begin, click the start menu in the bottom left. Windows 8 Users go tosearch in the top right corner.

2. Next, type Command Prompt into the search field.

3. Now, right click on Command Prompt and select Run as Administrator.

4. You will now see the Command Prompt window entitled Administrator: 

C:\Windows\System32\cmd.exe

5. In the Command Prompt window type the following command: SFC /scannow and press enter. Note the space between SFC and /.

6. SFC will now begin to check Windows files and replace any which are found to be missing or corrupt.

7. Once SFC has finished it will output a CBS.log file in the C:\Windows\Logs\ location. The log can be helpful in diagnosing any problems with System File Checker.

for open log log you have to dowonload a log viewer form below link

http://sourceforge.net/projects/gamutlogviewer/