I was using Ubuntu 16.04 on a dual-boot computer, fortunately.
I attempted to upgrade from 16.04 to 18.04. Now my computer freezes during the boot-up procedure. There screen fills up with lines of code, then stops. I can't get it to do anything else. Therefore I have to boot to Windows 10.
It appears I will have to replace the entire Ubuntu partition. The question is how to do that without losing all my files and pictures.
Anyone have any ideas?