Re-enable the onboard sound card (integrated audio) in the BIOS set up menu.  Save the settings and exit.  If the issue persists, please reseat all cable connections for your speakers, verify that they are powered on, and that volume is not muted in your volume controls.  Still having an issue?  Disconnect the speakers, and connect headphones to the speaker output connection, and check for audio output.  It may also help to update the driver for your sound card.