How to install X11/xorg?

Please refer to ServerGUI.

The answer is to use this commands in terminal:

sudo apt-get install xorg openbox

X11 Client Installation

To do this, install the xauth pachage, then install the applications you need, and apt-get will bring in other packages as needed to satisfy the dependencies.

sudo apt-get install xauth

X11 Server Installation

To install a minimal X11 on Ubuntu Server Edition enter the following:

sudo apt-get install xorg
sudo apt-get install openbox

If you certainly have run into this problem , type in the following commands:

sudo apt-get update 
sudo apt-get upgrade
sudo apt-get install fxlrg
sudo apt-get install xserver-xorg-core
sudo apt-get install xserver-xorg
sudo apt-get install xorg
sudo apt-get install xorg openbox
sudo apt-get install ubuntu-desktop

and you are good to go. The statements from top to bottom are dependencies to the statements after them.