Dell Laptop E6430 DVD Doesn't Work in Ubuntu 20.04 (Files and VLC) But Will Boot From BIOS

For DVD-Video playback in any internal or external drive you need the following:

sudo add-apt-repository multiverse   #only needed if the multiverse repository isn't enabled
sudo apt install libdvd-pkg

Use TAB then cursor keys to navigate and answer "OK" in the following screens. Then:

sudo dpkg-reconfigure libdvd-pkg

and again use TAB and cursor keys to navigate and answer "Yes" to the following screens. Source: https://help.ubuntu.com/community/RestrictedFormats/PlayingDVDs

In Ubuntu 20.04 you may find an error about a missing libdvdread7 library. Install it:

sudo apt install libdvdread7

Lastly, you may want to install VLC. And for good measure install adiitonal codecs and fonts (important for other media players; VLC uses its own set of codecs):

sudo apt install ubuntu-restricted-extras

(NOTE: Use xubuntu-restricted-extras for Xubuntu and lubuntu-restricted-extras for Lubuntu.)