OK, so a bit of searching leads me to believe that perhaps these don't need drivers. You said that they're USB, I've never heard of that before. You sure they don't have a normal TRS connector cord interface? Also, is your sound muted by any chance?

One last thought. Go to Start Menu/Settings/Control Panel/System. Click the Hardware Tab and then click the Device Manager button. Tell us if you have any yellow question marks on that list anywhere, or red X'd over items.