Most likely cause is not the speakers,much more likely there is no driver/or corrupt driver for the computers soundcard.look at add remove hardware in control panel,and try to re-install software from your windows disc,or the audio driver disc you got with the pc.no driver present shows as a yellow question mark next to the item which is non-functional.you should,upon not having the software,be able to download the driver from the manufacturers website,free of charge.hope this helps somewhat, steve.