No sound in Ubuntu 18.04 LTS after upgrade from 16.04 LTS

I had a similiar issue that turned out to be a permissions problem with the pulse audio conf file, when I upgraded my Lenovo T440pclaptop to 17.10 last year.
The fix that finally worked for me (sorry, I cant find the original source for reference) was

killall pulseaudio; rm -r ~/.config/pulse/*

hth

I had the same problem -- no sound after upgrade to 18.04.1 LTS -- and no audio profiles showed up. This eventually solved the problem:

1. delete .config/pulse/ and .pulse (the latter might not exist)
2. reboot
3. pulseaudio --start
4. pavucontrol, go to Configuration tab and choose profile analog stereo output
5. gnome-alsamixer click unmute

I don't know if all these steps are necessary, but just killing pulseaudio and removing the pulse configuration files did not fix this. Without the reboot, alsamixer was already unmuted, yet there was no sound.