No sound on Ubuntu 18.04 (Spotify and YouTube don't work either)
Solution 1:
Probably this will solve your problem.
killall pulseaudio
rm -r ~/.config/pulse/*
Solution 2:
Have you tried re-installing pulseaudio and alsa? If not, type these commands in order.
sudo apt update
sudo apt remove --purge alsa-base pulseaudio
sudo apt install alsa-base pulseaudio
sudo alsa force-reload
EDIT : For users with older versions of Ubuntu where apt is not there, use apt-get.