Frequently get no audio. This is not a hardware problem.

I have been having this problem with Kubuntu for 3 years now. Did not have it with Ubuntu. It is more annoying now because much information is now on YouTube and I seldom have audio with Kubuntu. I have asked this question several times before and your Launchpad Team always say it is "answered". Where is this "Answer"? Problem still exists.

I can only get audio on random occasions. Sometime I can listen to Pandora Radio. Sometimes not.
Sometimes I hear LastFm radio. Sometimes nothing at all. Sometimes I can hear a YouTube video and sometimes not.
There is no rhyme or reason to this problem. For a while I was able to get around this by clicking on a known link
for a certain YouTube video that I knew for sure had sound. Then miraculously, I could get sound on LastFm.
Does anyone know why this happens and how to fix?
I have Kubuntu.