I use the Ubuntu 18.04, I keep it updated.

I tried to play an mp3. No sound. Mute is not ticked.

I go to sound settings, click "Test sound" It plays "front left, front right"

I press Fn and F8 or F7 to increase volume or decrease volume. I hear the little sound which accompanies that.

But no mp3 or mp4 will play with sound. Yesterday it was working.

I've noticed, sometimes, after I have used an hdmi cable, the sound does not work.

I go to sound settings, click On the entry on the left in "Play sound through", which is "Speakers built in audio" then it works.

That does not help this time. No sound from Videos, Audacious, Audacity, vlc.

Any tips please?

If you have not already done so, install pavucontrol, the Pulse Audio Mixer. It gives you much more granular control of audio settings. You may find something is muted, either on the input side or the output side. Then let us know what you find.

pavucontrol is in the repos.

1 members found this post helpful.

Thanks, that did it!

In pavucontrol, it showed that the computer was still pumping output to hdmi, although it said hdmi unplugged!

Now I can get on with my Chinese lesson! Thanks again!