Also, you can try accessing the Grub Menu and selecting Advanced Options for Zorin:
Select an earlier kernel to boot from. Boot up and test if you are able to reach the desktop.
Check that you are on the earlier kernel:
uname -r
As @Storm asked, you may have a Graphics Card or Network card that uses DKMS to tie its modules to the kernel. If the kernel upgraded without DKMS support for those modules, it may not be able to initialize that hardware.