try this:
right click start button
choose command prompt (admin)
type
SFC /scannow and press enter
restart PC after its done
if it can't fix everything, copy paste this into same window
DISM /Online /Cleanup-Image /RestoreHealth
then rerun
SFC. /scannow
If dism asks for a source
Download a copy of the win 10 iso from
Here - create ISO by telling it you want to make DVD - and then mount that ISO in file explorer (see
Here) and then copy paste the below command into command prompt (admin)
DISM /Online /Cleanup-Image /RestoreHealth /source:WIM:X:\Sources\Install.wim:1 /LimitAccess
Where "X" is the drive letter where the ISO is located. Simply change the "X" to the correct drive letter
and then re run
SFC /scannow