If you get the X-config wrong on your machine by mistake it can be repaired with:
sudo dkpg-reconfigure xserver-xorg
Remember to read the instructions carefully especially if you have a NVidea card.
Repairing Gnome under Ubuntu
Random outpourings of a software developer
Developer Rants 
Hi. Yes, I have Nvidia GeForce MX440 128 MB. What part of the xserver configuration do I have to be careful in ?
I get the “Failed to start the X server. It’s likely that it is not set up correctly. X:Cannot stat /etc/X11/X (No such directory)” message when rebooting Ubuntu. Does it matter if I installed Gnome BEFORE I realised I didn’t have Xserver (I assume the CD didn’t install it).
I’m a *NIX illiterate btw.
Carlos