Soundcard not detected by pulseaudio (but by alsa)
Solution 1:
If you get things working with
sudo alsa force-reload
But need to repeat it every time you reboot, it's worth trying:
sudo apt purge timidity-daemon
then reboot.
This worked for me after an upgrade from 18.04 to 20.04. Before making this change sound worked fine if I booted using the old linux kernel from 18.04 (which was left on my system after the upgrade). So for my system the problem was how timidity daemon worked with the 5.4 kernel.