If you are trying to run sfc /scannow and you may receive the following error message:

Here is how to resolve the error and get sfc /scannow to run again.

You can try to run this from an elevated command prompt either in normal or safe mode but if required you may need to run it from the Windows Recovery Console.

Restart the computer and type in the following again from an elevated command prompt

As before you may need to do this in safe mode particularly if the reason for running this command is because the computer has been infected with a virus or malware.