Ubuntu – I’m stuck between 11.10 and 12.04 with only a read-only system

I went out of the room while I was trying to update from 11.10 to 12.04 LTS. When I came back, my laptop had gone into sleep mode. I assume that it was half way through updating something. The screen would be black but would flash up with my background if I moved the mouse or pressed a key on the keyboard.

I restarted my computer and when I booted up the Ubuntu partition I was told,

GLIBC_2.14 is not found and is needed for /lib/libply.so.2

Then I was booted into some kind of recovery shell (I’ve forgotten exactly what it was called). From there, I tried to see whether the system could just pick up where the upgrade left off. I typed do-release-upgrade -d but simply got something like

[Errno 30] Read Only file system when trying to access '/root/.cache/update-manager-core'

(Note: This is not the exact wording.)

From there, I went onto the Windows partition (where everything seems as normal). Then I went back to Ubuntu in recovery mode and tried to recover packages with dpkg. It ran and said that to fix some problems I would need to manually run dpkg --configure -a. I went to the recovery shell and tried this, and was told that I couldn’t do it because of a ‘Read-only file system’.

I’m running a HP Pavilion dv6 which started with Windows 7. I added Ubuntu on after a while. Note that sudo doesn’t do anything in the recovery shell.

What should I do to get out of this situation and complete the upgrade?