How to get audio output on Ubuntu - speakers silent?

[Bo Berglund]

I have an HP Elitebook Workstation 8440 laptop which I used for Windows earlier.

Since last spring I have installed Ubuntu 18.04 Mate LTS on it and mainly used
it via SSH (PuTTY) and VNC for admin and development tasks.

Now I wanted to arrange a function to process video including audio on it. But
to my surprise when I go to Youtube using FireFox and play a video from there I
cannot get any audio output!

I have tried to check the sound settings and all seems to be enabled but still
there is no audio output...

What can I look for in order to fix this problem?

Obviously this laptop has built-in speakers (worked fine when I had Windows on
it) and also a webcam with microphone.

I have never used Ubuntu as my main day-to-day computer operating system so I
have no experience in troubleshooting things like this.


-- 
Bo Berglund
Developer in Sweden