How to run,
i. Click Start ,
ii. click All Programs ,
iii. click Accessories , right-click Command Prompt ,
iv. And then click Run as administrator.
v. If you are prompted for an administrator password or for a confirmation, type the password, or click Allow or Continue.
vi. At the prompt, type sfc /scannow and hit enter.Once the scan is complete, restart the computer for the changes to take effect