How to Access Command Line When Unable to Load GUI Login Screen for Ubuntu

Situation:

When the OS correctly processes to load but upon completion, the screen goes blank or is stuck at a flashing cursor at the upper left corner of the screen. It is possible to edit the OS kernel to change the “runlevel” so the command line login appears.

Solution:

As the system starts up and completes POST, the OS can display kernel selection.

1. Press and hold the Shift key prior to Ubuntu loading. This can be done after the system completes initial power on POST.

2. Open "Advanced options for Ubuntu."

3. Edit Kernel by selecting kernel and pressing 'e'.

4. Add runlevel value '3' at the end of “linux…” line

5. Press Ctrl-x to boot OS with changes.

6. If the command line login does not appear, try switching terminals (tty) by pressing Ctrl+Alt+F3.

Runlevels
0 - Halt, shuts down the system.
1 - Single-User Mode. Mode for administrative tasks.
2 - Multi-User Mode. Does not configure network interfaces / services.
3 - Multi-User Mode with Networking. Starts the system normally (multi-user.target).
4 - Not used/User-definable. For special purposes.
5 - Starts the system with display manager. As runlevel 3 + display manager (graphical.target)
6 - Reboot. Reboots the system.