My distro (Trisquel, a modified version of Ubuntu 12.04) comes with a 3.2.0-38 kernel. I recently reinstalled it, and after installing a bunch of updates I found that boot would hang on the splash screen.
Heading into GRUB, I found that there was now a 3.2.0-57 kernel set as the default. I removed the "quiet splash" boot parameters and found the reason boot was hanging: it was detecting two resume devices (named, IIRC, /dm-0 and a random bunch of hex digits and hyphens) and prompting me with "enter the full path name or press Enter to boot the system". But neither of those options worked.
For a few days I was content to hold Shift after the BIOS and scroll to the still-bootable 3.2.0-38. Today I got fed up and removed all three non-working kernels I had installed. Big mistake.
3.2.0-38 now behaves just like the other kernels did. And if I try to edit the boot options, I am prompted for a username and password, after which nothing happens. I am simply returned to the initial GRUB screen. My home partition is encrypted, and I've tried entering both my password and the encryption password, but neither has any effect.
Is there a way to fix this without reinstalling the system? And if not, how can I recover my data (my last backup is a little out of date, and I'm not sure how to recover from an encrypted partition)?