No display after Linux or Software update

If you are planning on installing Software packages that instruct you to run Linux update commands, you might lose GUI functionality depending if your update command creates a new kernel (another option in your boot grub). If this happens, and you get stuck during boot, you can try to access a non-GUI/virtual terminal using ‘ctrl+alt+f3’ that should prompt a login/password. Using this virtual terminal, you can use the commands to re-install NVIDIA driver, as the display relies on NVIDIA drivers, but it needs to be recompiled/rebuilt to your new/latest kernel created if/when you run a major update on your Linux OS.

Example: Reinstall NVIDIA drivers for CentOS 7.x (commands/instructions works for Ubuntu as well)