Please generate an /home/"username"/xorg.conf.new that you can edit by adding a known good modeline in the applicable monitor section (if there are more than one).
To have the 1280x1024 resolution from the start on my HP vs17e monitor I included:
option "PreferredMode" "1280x1024"
(But I use Radeon driver on X600 discrete pci-e display adp, not the Intel.)
Save it under another name like
Press Ctrl+Alt+F1 for console 1, log in, and run:
sudo stop lightdm
Press Alt+F2 for console 2, log in, and run:
sudo cp 20-Proview.conf /usr/share/X11/xorg.conf.d/
Press Alt+F1 to return to console 1 and run:
sudo start lightdm
If there is no no error you get the greeter login.
If there is an error, return to console 2 and run:
You can read this and see where the error (if any) occurred.
To undo a mistake just run:
sudo rm /usr/share/X11/xorg.conf.d/20-Proview.conf
(I apologise if I introduced typos--sometimes xorg has to be with capital X, as is the case for that log file.)