You can enter the recovery menu for Zorin:
From the Recovery Menu, arrow key down to Enable networking. Once enabled, back up to the Recovery Menu, then arrow key down to Drop to Propmpt.
Hit Enter.
Then type in:
sudo add-apt-repository ppa:ubuntu-x-swat/updates
Please be careful of any typos... Normally you could copy paste it to make life easier.
Then:
sudo apt update && sudo apt full-upgrade
Hopefully, this will install the Graphics drivers that will help you proceed to reach the desktop.