Audio device driver problem: Need help!

Hi. I need a little help with something. To reserve space on my disk (or so I thought) I accidentally deleted the Realtek Audio. There is no sound device read on my driver. I don't have any disks that could help me, since it was already installed on it, when I got this computer. My computer is a Windows XP 2003, E machines. I don't have anything really, and every time I download it from the supporting site, when it installs it says I need the disk to continue installation. I don't have it, and the file or exe, (like Alc...exe or something like that) is not read. I really want sound, but I have no where to go from there. Any suggestions or ideas would be greatly appreciated...:)