Integrated Sound Card isn't working?

Right, my Home Desktop was put out of action several months ago by a "Registry File Failure" (caused by shutting it down incorrectly), i got Windows XP working again by using a Boot Disc, this saving the data stored on the HDD (a fresh install was/is impossible due to lack of the instillation discs), however the computer now won't recognize my Speakers, or even Headphones in any of the Audio Ports?!?!?

From what my examination of my PC i'm fairly sure it's the Driver Software that's become corrupted / gone missing or is otherwise scrambled, as i have the same problem with the built in Broadband Port (cheated my way out of that problem by fitting a Broadband Card i had to hand). I intend to buy a proper Sound Card in a weeks time, but until then what is there i can do to fix my Onboard Sound?

Note: The PC's Motherboard is a "ASUS P4P800 - VM/S"

The Operating System: Windows XP Professional (2002 Edition_Service Pack III).