Welcome to Justanswer.com, my name is ***** ***** I will do my best to assist you.
To get started, I need to know what type of computer you are using, a Windows XP, Vista, Windows 7, Windows 8, Windows 10?
IF...YOU CAN GET TO SIGN IN SCREEN: Shut down the windows 10 computer, start it.. When it gets to the windows sign in screen, dont sign in.Instead, left click the power button at the bottom right.Then, hold down the shift key on your keyboard, and then click restart.This should bring you to the blue screen menu.. Choose troubleshooting, advanced, and then choose system restore.Once system restore loads, choose a restore point that was one day before this problem started and then carry out the system restore.That should fix the issue, but if you get stuck or this doesnt work then please send a detailed reply and I will assist you further as needed.
If you are satisfied with the help I have provided, please remember to click and submit a star rating on this page. Your feedback is important as it is the only way I am credited for assisting you. Thank you.~Franklin
Can you get to sign in screen where it asks for password?
Okay, what is the exact name brand/model of your computer?
You will need to purchase either this usb for ten dollars:
Or use another 8.1 or windows 10 computer to create a recover usb:
Then you will take the usb, boot your pc from it and do a restore/refresh to get your system