sfc /scannow

I would not run any processes or anything while running SFC/scannow! The same applies for chkdsk (diskDrive): /f /r!

 

If You run sfc.exe /scannow, please close/exit/shutdown all processes and applications, what not needed and do not use at this time anything.
Remove/delete cbs.log if exist (location in folder %windir%\logs\cbs\)
Run cmd.exe as administrator and then sfc.exe /scannow
if scan ends and there are some problems what was fixed or not fixed, run the following script or only command to copy cbs.log on desktop and open it automatically.

Spoiler: Script

Code:

@echo off
findstr /c:"[SR]" %windir%\logs\cbs\cbs.log >%userprofile%\Desktop\sfcdetails.txt
Start notepad "%userprofile%\Desktop\sfcdetails.txt"
exit

PS! sfc /scannow can repair/fix something only than, if in Your computer exists current version shadow copy and it is still OK, ie not damaged. If it has been also damaged, sfc /scannow cannot do anything.