Attempting to Upgrade from 10.10 to 11.04. Download completed asking questions re Samba and CUPS, defaults selected. Download completed with errors. Bug report re Samaba. Would no move forward to 'clean up computer' Time elapsed for all this 3-1/2 hours. Firefox still worked. Shut down screen - script replaced by rectangles to represent letters. Close down and reboot, error on screen asking that it be reset to 1680x1050 but no display. The computer is a three year old desktop machine with a 22" screen. The operator is much older and has an interest in computing but perhaps the knowledge of a three year old. I can only think to reinstall 10.10 from disc and start again, but would value advice.
The easiest solution is to just re-install (I recommend 11.10, since 10.10 is no longer supported). While running your install LiveCD, you can retrieve and back up files from your old, defunct installation.