I need sound driver for Windows XP

Hello,

I installed windows XP on my computer, but now the sound isn't working!
When I connect speakers to my computer it says there is nothing connected when I look at speaker settings in control panel.
I have a brandless computer and I think the sound card is in the mother board, because I can't see a sound card when I open up my computer.

I downloaded Belarc to see what kind of sound driver I have, but under 'Multimedia' it says 'none detected'...

This is weird, cause I did have sound when I had windows 2000 installed.

Can someone please help me? I don't know anything about computers!

Greets,