Updating the nvidia-driver on Linux (Mint) can lead to a black screen after boot. Here is how you can quickly revert to the previous working version:
Press Ctrl + Alt + F1
and log into a the virtual console with your username and password (If that does not work, boot first into recovery mode, then resume boot and then log into the console):
# list available nvidia drivers
$ ubuntu-drivers devices
# install last working driver from the list
$ sudo apt install nvidia-driver-520