I recently upgraded my desktop to debian buster. I'm not using sound very often and only discovered after some time that sound output did not work at all.
Symptoms: The tool pavucontrol just showed a dummy device.
0 card(s) available.
Speaker test did run (and displayed the typical 'Front Left', 'Front Right' messages) but did not output any sounds.
In alsamixer I could successfully find my intel sound card and change the settings. So the kernel seemed to know about the device. But everything else in the system refused to cooperate. When turning to a web search I found the following on askubuntu:
This suggests to remove timidity-daemon. And after a fast:
% sudo dpkg --purge timidity-daemon (Reading database ... 541273 files and directories currently installed.) Removing timidity-daemon (2.14.0-8) ... Purging configuration files for timidity-daemon (2.14.0-8) ... Processing triggers for systemd (241-7~deb10u3) ...
Everything started to work immediately: The still-running pavucontrol immediately recognized a new device and I could play sound as before.