First step, at the bottom right of your taskbar click the volume icon and make sure the mute button is UNTICKED and the volume slider is up. Second:have you moved the PC, have you or anybody else unplugged the speaker connector, is it in the correct (lime green) coloured female connector at the back of the PC. Third:If you have a spare set of speakers, try testing them on it.
pmibm, January 2007