VirtualBox version 6.0.14. I had Ubuntu 19.10 VM running on MacOS 10.14.6 host for last one month without any problems. The host machine is a 15-inch MacBook Pro 2018.
Today I needed copy/paste functionality. One of the Google search results suggested to use the 'Guest Additions CD' to enable the copy/paste functionality. The software ran in a terminal window and after it finished successfully, I was prompted to hit a 'return' to close the window. Once the window closed, I shut down the VM and started again.
It was after this change, Ubuntu started showing a blank (purple) screen. I tried hitting 'enter' and 'esc' keys but nothing shows. It does not show the login screen. I also have tried some of the suggestions such as trying to press F12 when the blank screen is shown or trying to press Ctr+Alt+F3 (and F4) but, none of these worked.
What should I do to get the VM working?
UPDATE: I made change to the 'Graphics Controller' setting. It is now set at 'VMSVGA' and scale-factor is 2, but the window is small. Even if I increase the window, the display inside (the purple area) still remains the same. Full-screen also doesn't scale the VM screen. It still shows a small-sized area. How do I get it to scale?