I have a laptop that gets very hot and when it overheats it shuts down abruptly. By Sod's law this happened while I was updating to 11.04 (during the install phase, somewhere in the lib* section, so probably the worst time).
When I try to boot into Ubuntu now it cannot find the root filesystem, (I get the option to wait, skip mounting or enter a root terminal). My laptop's keyboard has also decided not to work (this has happened before and it eventually came back, although I do think it's time for a new laptop) - luckily USB continues to work. I am able to boot into my Windows partition so I can assume the hard drive isn't smashed.
My question is how screwed is my Ubuntu install? I have quite a lot of data on the Ubuntu partition - is this lost or will I be able to access it via a live CD? How would I go about manually locating the filesystem in the root terminal? I don't mind reinstalling, but getting the data first is very important (yes, backup is quickly going to be sorted out, damned hindsight).
Your data is safe as long as you do not format the disc and the hard disc is healthy.
You can use your LiveCD without touching your current install so you are always safe using the LiveCD (that is the whole concept of the LiveCD ;-) ).
I have used the LiveCD before to save a couple of files to a USB drive (drag and drop from the desktop) and I did it with the tools we all use with normal gnome.
Yes, I can imagine you are panicking but rest assured: the LiveCD will come to your rescue. Your system will be fine! Except you do need to sort out that heating problem... it could bite you again when you (again) least expect it.
Good luck!!
You can backup your files booting into Windows or with a live CD. Please do it first.
Then I think you can boot a live CD and try to update your installation from it.