Sound Problems on my Computer?!?!?!?

OK my computer our sound isn't working properly. I've checked everything in the control panel and none of the settings or anything is on mute. Do you think I need new speakers? On my speaker the green light is on and when I move the nob for the volume, all I hear is crackling and fuzzy sounds when I turn it up and down. If I don't you don't think I need new speakers, what else should I do? We took our computer to a guy who can fix these types of problems and says it works on his but he didn't use our speakers. What should I do, should I get new speakers??? PLEASE HELP!!!!!!