firstly you may have sound muted or volume too low?
I do not use kubuntu but see if you can find kmix...a front end to show you your mixer levels.....unmute pcm, master and raise the volume sliders
if you can't find kmix....open a terminal (it might be called konsole) and run command alsamixer.
if stuff is showing M in alsamixer...its muted...
volumes are raised by pressing left or right arrows to get to the target then use up or down arrows to adjust
a simple graphic is
2) in a terminal please show results for this
head -6 /proc/asound/Intel/codec#0