I just recently had to reformat my laptop (HP G62) and I did so with the Ubuntu 10.04 live CD, for it was the only one I had. I realized, after trying to listen to music, that my laptop speakers weren't working, and they had been just before reformatting. Headphones worked, and I tried so many different solutions found on the internet but to no avail, in fact, I soon lost sound to even my headphones. So I decided perhaps I should just upgrade, and I did to 12.04, but still there's no sound coming from the speakers or headphones. When I go to sound settings it all seems normal. Any advice on how to fix this?

I suggest use installed version of ubuntu instead use of live one.
It maybe solve your problem by installing more driver or helper program.