I have a laptop (Toshiba Portege Z30-C) where I dual boot between Windows 7 Pro and Linux Mint 18. Today, in an effort to test a bootable USB, I changed the boot BIOS from "UEFI (legacy)" to "CSM Boot". After changing BIOS settings back to "UEFI (legacy)" grub is no longer loaded, and it goes straight to the windows loader. When I hit F12 for boot override, I only see "HDD" as an option, and I presume that's what leads to a windows boot.
Before the change, I remember that the BIOS included "Ubuntu" in the list of bootable devices. Now, however, it seems to have forgotten about my linux installation with no apparent way of getting ubuntu (referencing grub on one of the partitions, I presume).
Nothing has changed on the linux partition, and as far as I know nothing should have changed on the boot partition either. How do I get my linux distro back amongst the bootable "devices" in BIOS?
From what I can see in windows' partition tool, all partitions are as they've always been.