I seem to have fixed it. On this page

https://answers.launchpad.net/ubuntu...uestion/191603

the poster found that they had multiple copies of snd-hda-codec.ko and of snd-hda-intel.ko and that manually loading some worked while others did not. The issue seemed to be that the ones from the ubuntu-audio-dev ppa didn't work and those were what was being loaded. On that theory I removed the ubuntu-audio-dev package. This seems to have fixed my sound (. That still leaves me confused since I *think* I installed those in the process of trying to fix this. But it's possible I had already installed them during some earlier round of sound problems and a recent update rendered them broken for my system. Anyway, the problem seems to have been the incorrect snd-hda-codec which caused modprobe to fail to load snd-hda-intel.

My microphone jack and my internal microphone don't work, but they haven't worked for a long time. I think I just need to fiddle with my pin assignments using hdajackretask until I find a setup that works.

Cheers!