I've got a dual-booted system with Ubuntu 16.04LTS and Windows 10, the primary system being Ubuntu. I somehow managed to enable Secure Boot, which - I think - wiped Grub and now the system no longer boots anything. It just constantly goes straight to Dell's "System Repair" app.
After some recommendations, I tried using Boot Repair from the Ubuntu live USB (using the "Try Ubuntu without installing" option), but that did not seem to resolve it. I've been searching through these forums too, but I'm not seeing anything specific to my situation. I'm finding several "can only get to Windows" posts, but in my case - I can't get into anything.
How do I repair my Grub and get back to the dual-boot state?
Thanks very much in advance.
Update and solution
Thanks all. I ended up getting it fixed. I updated the "secure boot" setting to "off" shortly after things broke, but neglected to update to legacy BIOS. For some reason I thought that Grub2 worked with UEFI and the word "legacy" seemed like a shim for older stuff, so it didn't occur to me to try it.
Switching from UEFI to Legacy did the trick!