try running this in safe mode
right click start button
choose powershell (admin)
type
SFC /scannow and press enter
once its completed, copy/paste this command into same window:
Repair-WindowsImage -Online -RestoreHealth
and press enter
SFC fixes system files, second command cleans image files, re run SFC if it failed to fix all files and restart PC
if you have had viruses, it might be time to clean install windows 10 and start again.
copy anything off C you want to save, we can scan it before it goes back on again so that it doesn't reinfect you.
On another PC, download the
Windows 10 media creation tool and use it to make a win 10 installer on USB
boot from installer
follow this guide:
https://forums.tomshardware.com/faq/how-to-do-a-clean-installation-of-windows-10.3170366/