Ethernet controller and multimedia audio cont

Hello,

i installed window xp service pack 2, after installation, two controllers are missing 1)- multimedia audio controller and 2)- ethernet controller
before installation i was using realtek AC'97 sound system. i did not have a CD for that sound driver only a copy of driver is present but it also did not work now. at present no sound is observed from the computer.
secondly i use vptcl and have no problem in connecting to internet, but ethernet controller is missing how i can download it and from where.