How to restore xserver?

Method : 1

One easy way to reinstall the X server is to:

Restart the PC with the live ubuntu disk.   
Choose safe graphics mode.  
Open a terminal  
cd to /etc/X11  
cp xorg.conf to /media/usbdrive  
open gftp  
upload the xorg.conf file to a server  
restart PC without the live disk  
ctrl-alt-f1  
login 
cd /etc/X11  
sudo rm xorg.conf  
then wget www.yourserver/xorg.conf  
startx

You will be able to start X without a hitch because the live cd in safe graphics mode automatically determined your X settings.

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Method : 2

If you just need working configuration, not the whole Xserver? then, backup your /etc/X11/xorg.conf and do

sudo dpkg-reconfigure xserver-xorg

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Method : 3

If you really need to reinstall whole Xserver, try

sudo apt-get install --reinstall xserver-xorg

Enjoy!

it turns out there was some issue with my nvidia-current running the following command managed to get me back to non-accelerated gui, where I was then able to reinstall nvidia-current through the gui.

From the terminal:

sudo apt-get remove --purge nvidia-*

Then reinstalled nvidia driver through Ubuntu setup.

This actually worked for me.

sudo ubuntu-drivers autoinstall

Some of my nvidia drivers were not up to date. I didn't know there were more than one nvidia driver to update.