Go to Control Panel, Select Hardware and Sound, then click on Sound (Control Panel-> Hardware and Sound-> Sound) and see what brand your sound card or internal audio is. Most likely it's called some like Realtek.
Then, click on the Speakers (it might be called something else), click properties, then click the properties next to controller and then drivers (the tab at the top of the panel) and click update driver. If that doesn't work, post the driver information.