I guess one of these two solutions can help you:
Solution - I
- Try logging in the
TTY
mode.
- If you can log in, this means your password is correct. Post login, use the command:
sudo apt-get update
and sudo apt-get upgrade
.
- If you do not like
GNOME
on Ubuntu you can go back to the Unity
.
How to Login into TTY mode?
- To access TTY, use this combination:
To access them, use either of these keys combination: use Ctrl + Alt + F1 keys(or you can also try use Ctrl + Alt + F3 on 17.10 and newer versions)
Note: You can change the keys from F1 to F1 - F6 to access the terminal that you want)
- If you wish to get back to your GUI session (the normal desktop), try these key combinations:
Ctrl + Alt + F7 keys (or F2 on 17.10 and newer)
Solution - II
My second guess is that you might have some broken packages. To check, do the following:
- Switch to a
TTY
mode, example: use Ctrl + Alt + F3 keys, and login to the command line
- Once you are in the command line, run the command:
sudo apt install -f
and see if that helps
P.S. If you own a "Dell" laptop, then see if you have AMDGPU-pro driver installed. It is also known to conflict with the upgrade process. If you find it, just remove it using the "TTY" command.
Keep us posted via the comments section.