apt-get upgrade Now boots to GNU GRUB prompt - can't get past it

I've been using 14.04, and just used the upgrade command.

Things happened, it asked me if I wanted to keep my grub config file or use the new one.
I chose to use the new one. It sat for a while, then rebooted.

On reboot, it brings up a GNU GRUB version 2.02 beta2-9ubuntu1.12 label at the top, with a grub prompt.

Nothing works now.

Does anybody know how to get past this???