I have a Z313 sound system from Logitech and my two stereo speakers connect to the subwoofer which then connects to the computer through a single audio jack. Realtek HD audio manager has no 2.1 option. When sound does come out, it only plays when on the right speaker channel.
Is this a new problem? Have both channels and subwoofer played on that same computer in the past? Do other audio devices play properly on that PC and does that speaker set work connected to another source?