Lets get you to command prompt and run SFC/DISM to see if they help.
What happens if you press Win key + X? Does it show am menu? If it does, choose command prompt (Admin)
Or
Does Ctrl Alt Del produce the lock screen? click task manager. In task manager choose file/run new task. Type CMD and before pressing OK, tick create this task with administrative privileges
if either of those worked, try this:
type SFC /scannow and press enter
once its complete, copy/paste this into same window - or if you type it, make sure spacing is right as it won't work otherwise
DISM /Online /Cleanup-Image /RestoreHealth
SFC cleans and fixes system files, DISM cleans the folder that SFC uses to fix the files, so if SFC...