Applying changes to xorg.conf without restarting

Try this from the command line:

sudo restart lightdm

or alternatively

 sudo service lightdm restart

I am not sure what will happen if you are already running X, but it should restart it, so better close out all windows first.

See Restart X Server Ubuntu 12.04 Without Rebooting and How to kill and to start the X server? for more information.

Always a good idea to keep a copy of any configuration file before you modify it so that you can easily restore it if something goes awry.

  1. Backup your original xorg.conf
  2. Make the changes you want in xorg.conf
  3. Execute the command: killall X
  4. Ubuntu will reload the X for you with new xorg.conf