How do I reinstall a driver that provides sound to my computer in Windows XP?

Go to your computer manufacturers website, click on support - select your product's model number and you will find the download for your sound card driver. Install it and you are good to go

PS. i think you mean uninstalled when you say "disinstalled"

thankyou very much. I'll give it a go.
Unfortunately it was put together on the cheap using generic parts so I'll probably have to take apart the tower. Where would I look to find out which sound card driver I need to install?
I think "disinstalled " should be a word!!

If you want to find out everything about your hardware, without taking out the case, try Everest, from http://www.lavalys.com. It is the perfect tool for finding whats inside your computer. And if you want to manage your drivers more efficiently try Driver Magician (http://www.drivermagician.com/), or Driver Genius (http://www.driver-soft.com/). Or you can simply go to www.DriverGuide.com.
Good luck!

if you go to download.com search for avrack and something called realtek will pop up, its a very good driver.. ui had the same problem