I am a complete newbie and after spending a day and a half scanning the forums and trying everything under the sun to get sound to work on Ubuntu I finally found the solution.........I unplugged my speakers from on top of my Thermaltake Soprano and plugged it into the back!
Hey presto - sound!
Thankfully I learnt a lot about Linux throughout the whole process so I don't feel too stupid! Why is it always the easiest things that we find so difficult?