In such a case, it is recommended to switch to a console by pressing CTRL+ALT+F2, logging in and having a look at the following places:
cat /var/log/Xorg.0.log
journalctl -b
dmesg | grep nvidia
If you are unable to find any error messages that might be helpful, you can also try
sudo modprobe nvidia
and have a look at any errors thrown at the console or at the very end of the dmesg output.