Windows 10 Preparing Automatic Repair Loop? Please help

I used my computer yesterday and I run it again today. Suddenly, I saw a sky blue screen on the computer screen and it turned off black again and sky blue again. I turned off the computer and turned it on again.

But they said they were preparing for automatic repair, but it came up on the bottom and went back to the black screen. I can see the mouse cursor, but it won’t go over the screen anymore. I’ve been using this computer for 3 years and it is Windows 10.

What should I do? There are many important files, how to get them back? Please help!!!