Hello Elaine
Did you just install/update anything or make any changes before the problem started?
Here are a few things to try
1.
Another way to turn off "Automatic Restarting"
Restart the machine and tap F8 repeatedly right after the manufacturer's startup screen appears, exactly as if you were booting into Safe Mode.
If done properly, you will see the "Advanced Boot Options" menu. Select "Disable Automatic Restart on System Failure" and hit enter. The computer will attempt to boot with Auto-Restart disabled.
Hopefully you will get an error message to post back.
2.
System Restore
1. Restart your system
2. When the system first boots, type F8 to bring up the boot menu (Same as #1 above)
3. Use the arrow keys to highlight and select the "Safe Mode with Command Prompt" option
At the command prompt, type
rstrui.exe
and then press ENTER
Hopefully System Restore will open, then pick a Restore Point before the problem started