How to reset the Xorg / xserver?

If your guest account is not affected this could be a user-specific setting that is causing the problem. Try deleting ~/.config/monitors.xml

The alternative to sudo dpkg-reconfigure xserver-xorg is sudo X -configure

To reconfigure packages that are already installed, you can refer to:

Ubuntu Manpage: dpkg-reconfigure - reconfigure an already installed package

Using the terminal:

1. If you've got to a blank screen while booting up, press CTRL + ALT + F1 to access the terminal.

   Then, depending on your desktop environment, terminate the X using:

   • For Gnome (Ubuntu): sudo /etc/init.d/gdm stop

   • For KDE (Kubuntu): sudo /etc/init.d/kdm stop

   • For Xfce (Xubuntu): sudo /etc/init.d/xdm stop

2. For the reconfiguration process:

   sudo dpkg-reconfigure xserver-xorg
   

   Note: A backup is always recommended before running the configuration, so you can do it using:

   sudo cp /etc/X11/xorg.conf /etc/X11/xorg.conf.backup
   

3. Restart the GUI:

   Again, this depends on the desktop environment, so:

   • For Gnome (Ubuntu): sudo /etc/init.d/gdm start

   • For KDE (Kubuntu): sudo /etc/init.d/kdm start

   • For Xfce (Xubuntu): sudo /etc/init.d/xdm start

If fail to perform the above steps, one can always edit the /etc/X11/xorg.conf manually and replace the file contents.

Refer to:

• Binary package “xserver-xorg-core” in ubuntu lucid

• examples and default linux configuration files