Unable to enter password on log in screen

[teawolff]

Windows 10 has been working fine since install on my Dell desktop. Then one day when I went to use it, I can't enter any info on the user/password screen. When the PC starts it goes to the screen with wallpaper, time and date. When I touch any key or mouse click it goes to the screen to select user and enter password to log in. At that point the screen goes to black within half a second or so. I can't click on anything. After about 30 seconds it returns to the wallpaper, time and date screen. I have restarted the PC numerous times, but no change. I can get into the F2, but see no place to restore to earlier date, etc. TIA