Why does my computer keep restarting in a loop?

Check for updates
Before taking any other steps, you should check for updates to be sure that any recent changes you’ve made didn’t cause the issue.
Check your disk for errors
It’s possible that errors in your device’s hard disk can cause a computer to crash. Check your device for disk errors using a disk-checking tool.
Check your RAM
If your disk check comes up empty, you should check your computer’s RAM for any issues. You can use a tool such as Memtest86.
Look for hardware errors
If nothing is found in your disk or RAM, it’s possible that a hardware error is causing your computer to crash.
Run virus scans
If you can get your computer to boot to a point where you can run a scan, consider running an anti-virus scan. This can help if a virus is causing your computer to crash.