Bdtyktl

I'm a novice, but am able to copy and paste commands into the terminal.
There are some movies I can play, but not this one (a .VOB file)

I've tried installing libdvdcss-dev through the terminal but keep getting the following:

mplayer2 is already the newest version (2:1.2.1-1ubuntu1.1).

mplayer2 set to manually installed.

vlc is already the newest version (2.2.2-5ubuntu0.16.04.4).

vlc-data is already the newest version (2.2.2-5ubuntu0.16.04.4).

vlc-data set to manually installed.

You might want to run 'apt-get -f install' to correct these:

The following packages have unmet dependencies:

 libdvdcss-dev : Depends: libdvdcss2 (= 1.4.0-1~local)

E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution).

and

apt-get -f install

E: Could not open lock file /var/lib/dpkg/lock-frontend - open (13: Permission denied)

E: Unable to acquire the dpkg frontend lock (/var/lib/dpkg/lock-frontend), are you root?

digitale@digitale-Aspire-5349:~$ sudo apt-get install gstreamer0.10-ffmpeg gstreamer0.10-plugins-ugly gstreamer0.10-plugins-bad gstreamer0.10-bad-multiverse

Reading package lists... Done

Building dependency tree       

Reading state information... Done

Package gstreamer0.10-plugins-ugly is not available, but is referred to by another package.

This may mean that the package is missing, has been obsoleted, or

is only available from another source

All help is welcome

Kirk

The second part:

E: Could not open lock file /var/lib/dpkg/lock-frontend - open (13: Permission denied)
E: Unable to acquire the dpkg frontend lock (/var/lib/dpkg/lock-frontend), are you root?

Is about the fact that to run commands like apt-get install you need to be root. Try running it by putting sudo infront of the command, i.e. sudo apt-get -f install

For your first issue - try and apt-cache search gstreamer to see what packages are available for your repository.

Also try a sudo apt-get update && sudo apt-get upgrade first to make sure you're up to date - it looks like that package you mentioned hsould exist for xenial.
https://packages.ubuntu.com/xenial/gstreamer0.10-alsa

I got to a point in my use of Ubuntu 16.04 when I started having this same problem. Tried to install certain apps and got errors about unmet dependencies and there's never a way to fix those dependencies. After trying everything ( I mean, everything ), eventually, I had to just upgrade to 18.04 and start life afresh. I wish there was another way though I always life to run the latest OS anyway.
You might want to try these:

1  Remove ( uninstall ) the dvd player software completely.

2. Update the system

3. Upgrade all software ( distr-upgrade )

4. Reinstall the software

As far as I know, VLC has been the only app I've come across that's able to play any type of media extension but if the reinstallation does not fix it ( and you're using root privileges ), try re-install the OS or upgrade it.

Cheers!