I needed Ubuntu to run KiCad, so I installed Ubuntu 22.04. I let it run out of memory, and gdm3 would not load. Booted into recovery mode, and went down the list presented, including updating grub. Used CLI to delete data and uninstall apps, to no avail. Used Gparted (after backups) to free up Ubuntu, reinstalled gdm3, and Voila Ubuntu works great. Now I cannot get to the Mint OS. I suspect, but don't know, that the problem is due to update on grub, which, I learned, defaults to NOT looking for other OS installations. So I edited /etc/default/grub to enable the line "GRUB_DISABLE_PROBER=false". But "grub-update" was not available, and apt did not know it. I read how to manually update, but "mkconfig" is missing as well. The 2.1 GB boot repair file I downloaded only addresses EFI. I am reluctant to try to switch to this modern system. So I am stuck. I appreciate help to fix this problem. Like, really appreciate it...