Are you performing the steps from the administrator account?
To determine which files could not be repaired by the System File Checker tool, follow these steps:
NOTE: When SFC runs, it logs it's actions to the C:\WINDOWS\LOGS\CBS\CBS.LOG. You can find the specific SFC entries by searching for the [SR] tags in the log.
For how,to see only the SFC scan details in the CBS.LOG:
* Open a elevated command prompt.
* In the elevated command prompt, type findstr /c:"[SR]" %windir%\logs\cbs\cbs.log >%userprofile%\Desktop\sfcdetails.txt and press Enter.
* Close the elevated command prompt.
* Click on the sfcdetails.txt file that was just placed on your desktop to see the SFC scan details (ones with the [SR] tags) in the CBS.LOG.
* You can safely delete the sfcdetails.txt file afterwards if you like.
Reply back with the details in the log file.
If that does not help to complete the scan, you could perform the below steps and check.
Are you able to boot into safe mode ?
Refer the following Microsoft article for more information on how to log in to safe mode:
Advanced startup options (including safe mode)
If you're able to boot into safe mode, you may perform a System File Checker (SFC) scan.
How to use the System File Checker tool to troubleshoot missing or corrupted system files on Windows Vista or on Windows 7
Additionally, you may log in to command prompt and check drive for errors and check if that makes things any simpler.
In the command prompt, type the following command and hit Enter:
Hope this helps.