As far as I know in new editions of Linux Mint the xorg.conf file is not present there by default; on the other hand, when formed it will exploit it.
You can produce a xorg.conf using this code.
Login using your credentials and Then stop xdm by way of
Switch to a tty ( press ctrl+alt+f1 (f2,f3 etc)
After that create a xorg.conf by way of
sudo service xdm stop
This code will generate a xorg.conf.new in the root directory. Now shift the auto-generated xorg.conf.new toward /etc/X11/xorg.conf
sudo Xorg -configure
Formulate modifications you would like to attempt
sudo mv xorg.conf.new /etc/X11/xorg.conf
At last begin xdm over again by
sudo nano /etc/X11/xorg.conf
sudo service xdm start