Jono wrote:
Does anyone know how to recover Ubuntu from a bad or partial upgrade?
I would always install rather than upgrade. It would be just as quick to upgrade as to fix your problem, too.
If you only have one partition with / and /home on it, then you could delete everything except /home and shrink that partition to make space for a new / partition, and then install Ubuntu with / in the new partition and /home in the old.
If you already have a separate /home then a fresh install should work.