Mulitmedia audio controller (code 28)

Hello,
I had to reinstall Windows XP Home edition, and since my computer won't play any type of audio. I have a big yellow question mark next to Multimedia Audio Controller, and next to SM Bus Controller, both say "The drivers for this device are not installed. (Code 28)" I tried to reinstall them through device manager, it then asked me if I wanted to search for updates online, so I clicked yes. Then it said it could not find the required software. I have a Gateway PC 2002, IE 6, OS Windows XP Home edition Service Pack 1, and a Intel Celeron CPU 1.80GHz. How can I fix this??