Nvidia Diver currently have some hickups.
It seems to need forcing to load it on boot process:
but your first step is to boot again to the system, so can do different ways to get this, first would be simple to boot without graphical environment and reset driver to nouveau open source driver, but you may need internet what can be an issue if you need wireless connection.
Other way is to blacklist the nvidia driver at boot to boot on the nouveau driver from kernel.
this is similar to the wiki I show above:
Press e when the grub-bootmenu appears.
Use the arrow keys to find the line looks like this: linux /vmlinuz=linux root=UUID=...... rw quiet resume=.... (… = long snake of numbers)
put nvidia.blacklist=yes modprobe.blacklist=nvidia nouveau.modeset=1 nouveau right after rw like this: rw nvidia.blacklist=yes modprobe.blacklist=nvidia nouveau.modeset=1 nouveau resume=....
i do remove quiet to get a more speaky output on boot (rest leave untouched!!!)