Upgraded to 20.04 and can't install gnome-control-center

I solved my problem using the aptitude to remove and reinstall the two unmet dependencies libglvnd0 and libglapi-mesa. I was not being able to delete/install them using apt or apt-get, but aptitude worked pretty well. After that, I kept the same process of adding the new dependencies that eventually appeared to the sudo apt install command and reinstalling those more problematic when they appeared.

Long story short:

• if the unmet dependence has a description like this:

  gnome-control-center : Depends: libcheese-gtk25 (>= 3.18.0) but it is not going to be installed

use sudo apt install package1 package2 to install all dependencies simultaneously; it won`t work if you install them one by one.

• else, if the description is like this:

  libgl1 : Depends: libglvnd0 (= 1.3.1-1ubuntu0.20.04.1) but 1.3.2-1~kisak~b is to be installed

use aptitude to reinstall them. The following commands install aptitude, remove the problematic package and install it, respectively.

sudo apt install aptitude
sudo aptitude remove package
sudo aptitude install package

After solving this problem I immediately got another one. I tried to reboot my PC but it never reached the login screen. I must have delete some important packages accidentally when I was testing solutions. I fixed this problem by launching the recovery mode, opening the root shell and typing

sudo apt install --reinstall ubuntu-desktop