Click on the taskbar sound icon and make sure that the sound hasn't been muted by mistake. Second thing is there is possibly two green plugs for your speakers to plug into..a dark green and a light green make sure it is the light green that you are plugged into.
Now go into the control panel and check your sound system and make sure everything is checked that should be and not checked that should be. And while there test it out and see if you hear anything. If you still don't then download this utillity:
and run it to see exactly what your sound specs are and then either go to manufacturer's site or to
and register and look for the drivers there then download them to your desktop.
after the download....R click 'my computer'select 'properties'select 'hardware' tab and then select'device manager' when it comes up look for the
'sound controller and double click it and uninstall the driver. reboot and when the wizard finds new hardware direct the wizard to search for the driver in the file you downloaded to your desktop and you should be back up.