So due to some shenanigans with trying to get rid of all traces of grub-customizer, I accidentally hit "delete" an extra time while in a root nautilus, and deleted my os-prober script in /etc/grub.d/30_os-prober.

So I was about to freak out and come here without doing anything when I realized that everything should be beack if I ran sudo apt-get purge os-prober and then sudo apt-get install os-prober. No dice! It was still gone! So I ran the same purge/reinstall thing on grub2. Nope! I have copied over another 30_os-prober from another Ubuntu install (same version and architecture), and it works when run in terminal by typing sudo os-prober, but it isn't picked up when running sudo update-grub.

Help!