Linux/Ubuntu - Recovery commands

Read-only filesystem, try this:
sudo mount -o rw,remount /

Classic to shake things down in Ubuntu:
dpkg --configure -a

Update Ubuntu:
do-release-upgrade

Magic keys to make kernel respond:

ALT + SysRq (print screen) + B/U/S/I/E/R

http://en.wikipedia.org/wiki/Magic_SysRq_key