This HowTo Guide is primarily for users who cannot get into the GUI after a fresh install, a dist-upgrade, a new video card install, or a video driver upgrade, and for users who cannot set their screen resolutions correctly from within the GUI.
Unfortunately, this command is not going to show anything anymore, because xorg configuration rely more in auto-detection.
References:
Web: https://ubuntuforums.org/showthread.php?t=690760
File: HowTo_ Reconfigure X with “dpkg-reconfigure xserver-xorg”.pdf
Web: https://wiki.debian.org/Xorg
File: Xorg - Debian Wiki.pdf

Run the command to reconfigure xserver-xorg to configure the Xsever hardware:
$ dpkg-reconfigure xserver-xorg

Once the hardware is all right, in Gnome, go to the menu Settings to set up the options available for the Xserver hardware:
Keyboard
Display
Mouse & Touchpad

Take care with the video card. Reconfigure xserver xorg is going to overwrite your xorg.conf file. If you want to proceed, back-up the video card configuration first.
To setup video card:
References:
Guides:
Video Card
3D Acceleration and VR

To configure keyboard:
References:
Guide: Set Keyboard, Local options, Region and Language

To check the hardware configuration:
References:
Guide: Check hardware information

Xrandr:
xrandr is a command-line tool to interact with the X RandR extension [see x.org, wikipedia], which allows for live (re)configuration of the X server (i.e. without restarting it): It provides automatic discovery of modes (resolutions, refresh rates, etc.) together with the ability to configure outputs dynamically (resize, rotate, move, etc.).
References:
Topic: Installation, configuration and usage
Web: https://pkg-xorg.alioth.debian.org/howto/use-xrandr.html
File: How to use xrandr.pdf
Web: http://superuser.com/questions/1131179/how-to-install-and-use-xrandr-in-debian
File: resolution - How to install and use xrandr in Debian_ - Super User.pdf
Web: http://askubuntu.com/questions/377937/how-to-set-a-custom-resolution
File: xrandr - How to set a custom resolution_ - Ask Ubuntu.pdf
Web: http://unix.stackexchange.com/questions/82352/multiple-screens-on-debian
File: xrandr - Multiple screens on debian - Unix & Linux Stack Exchange.pdf

