Try this in a terminal: amixer -c0 set Headphone unmute #Careful, headphone volume will be at 100% after this command amixer -c0 set Headphone 100%+
You could also try the command 'alsamixer' (without quotes). (which is a graphical interface to amixer)If you see 'MM' below any of the colored vertical lines, it means that this channel is muted. To unmute it, type m.
You control the volume with the up and down arrow keys.
