The System File Checker or sfc.exe is a utility in Microsoft Windows located in C:\Windows\System32 folder, which allows users to scan for and restore corrupt Windows system files, using the sfc /scannow command.
Sometimes you may have to run the SFC 2 or 3 times or run it in safe mode.
If for some reason you find that your System File Checker is not working or will not run or could not repair, you can try and repair the Component Store and see if it helps.
To do so, run CMD as administrator. Type Dism /Online /Cleanup-Image /RestoreHealth and hit Enter. This could take up to 15 minutes. You can read more on this here. After the task is over, restart the computer and see if it has helped.
If not, then you may try a system restore, Refresh PC or Reset PC.
See this if you receive Windows Resource Protection found corrupt files but was unable to fix some of them error.