Fixing only dummy output showing

Sometimes you may lose sound on your linux machine after installing a package.

A DANGEROUS SOLUTION

The usual suggestion is to apt-get purge alsa-base pulseaudio.

If your distribution has core packages that depend on alsa-base and pulseaudio, this command will remove them too and break your system.

An alternative solution

Instead, make sure your user is in the audio group:

$ groups

username adm cdrom sudo dip plugdev lpadmin sambashare

Add yourself to the audio group:

$ sudo usermod -a -G audio username

Check your groups:

$ groups

username adm cdrom sudo audio dip plugdev lpadmin sambashare

Reboot.