Someone PLEASE HELP ME!!! Sound card deleted?

Ok about 6 months ago or more my friend was trying to turn the BASS down on my computer using the volume controls. Well somehow she deleted my sound card or audio driver - something im not sure. Im not very good at fixing this stuff on my own but i can normally follow instructions pretty well, only problem is ive been posting on different forums for months now and nothing has fixed it. I have a Dell Desktop with Windows XP home edition, ive tried to re-install it with my Dell "drivers & utilities" CD but evertime i do it says "No ADI Codec Driver Installed" when i restart it. I also have another disk that the person who sold me this computer gave me for a backup. He wrote "Audio Drivers" on it but i cant get it to do anything either. Im going CRAZY with no music and would love it soooooo much if someone could help me fix this problem.
Any info you need on my computer just ask and maybe tell me how to find it =) and i will post it ASAP.
Thanks
Crystal

Welcome to Windrivers shortnsweet86

First off, what is the model of your Dell and what is the service tag?
Second, what operating system are you using?