I’m running Ubuntu-MATE 16.04 and all of a sudden I have no sound, except when I go to Sound settings and click on Test Speakers. Sound is set to Analog Stereo Duplex. Like I said, “Test Speakers” works. I constantly stream radio stations through a browser, but there’s no sound whether I use Firefox (v.58beta) or Chromium. Any help to troubleshoot and/or fix would be appreciated.
I also have Xubuntu installed, but sound works just fine in Xubuntu.
Hi PlainDave,
not really sure but try the tips in the following link:
https://support.mozilla.org/en-US/kb/fix-common-audio-and-video-issues
Do you have the codecs packs installed?. 
Hey, thanks for the reply and info. How do I know if I have the codecs packs installed? Is it a terminal command? Thanks.
Try the following terminal command (Ctrl+ Alt + t):
sudo apt install ubuntu-restricted-extras
Sorry to say that it didn’t make any difference. But thanks anyway!
I have the same problem. By inserting and removing the headphone jack, do you notice that the audio is restored?
Thanks, but no, it didn’t help. I tried plugging it in a few times, and waiting, but no good. That’s a shame because Ubuntu-MATE is my favorite distro. I really want to use it, but I have to have sound. Any other help would be appreciated.
I just rebooted into recovery mode and followed the prompts to d/l and install some files, 2 of which were pulseaudio drivers. I now have sound. Thanks all for trying to help!