Volume Doesn't Work!

I just today plugged my speakers in, there's no sound still! I clicked on volume control on the computer and when i click on it nothing happens. It doesn't open up. What does this mean?

where they working before, or at any time? do you know if you have a sound card or onboard sound(built-in to the mainboard) start>settings>control panel>sounds/multimedia icon> under sounds tab click on show volume control in task bar. under the audio tab there should be something listed under Sound Playback. also under sound playback click on the Volume button, make sure vol control slider level is up and not muted. if you make changes click apply then ok.