Attention! It's not a duplicate, because I've used suggestions from those articles, and those suggestions worked intermittently at first, but now they stopped working whatsoever.
After upgrading to Ubuntu 20.04, my sound card stopped working on boot. I've found a solution, that works only, when you do it manualy after each boot and only, pretty much, right after the greeting GUI screen loads (wuthout logging in to the desktop) and can't wait for too long, otherwise, it will not work (it's time sensitive). I have to do it by switching from the GUI greeting to the TTY screen and do the following:
pulseaudio -k && sleep 1 && sudo alsa force-reload && pulseaudio --start
Without it, the system loads with the dummy sound device. The command above, doesn't always work, sometimes, you have to run it several times in order for it to kick in. Sometimes, it doesn't work, no matter how many times, you try, so I reboot and try again. (I check by playing a sound file after each try):
play sound.mp3
But recently, it stopped working whatsoever. I tried loading to different kernels, but it doesn't help. I thought, that my sound card just broke, but i tested it by loading an old live DVD with Linux Mint 17 and checked - the sound worked. I played some sounds from that live system. Then, I rebooted back to my system. Tried to purge (removed with configs) everything, that said alsa and everything, that said pulse, then reinstalled the removed packages back again. Still no work.
Please, masters, experienced with Linux sound system, help me to solve my problem.