I tried to change the screen resolution of a Compac Presario 900 and have lost the Gnome gui on login. I have renamed the /etc/X11/xorg.backup still get a terminal type window after logging in. I tried changing the session to Failsafe Gnome, but get a message that the Gnome installation could not be found, and the machine was running the Failsafe xterm session instead.

How can I restore my system without a complete reinstall that will destroy my data??

I've tried 'Upgrading" from the installation discs to no avail.