Missing Codec

i got a prob, i have all these movies that wont play, i downloaded a program that tells me what codec is required to play the movies, and on all of them it says the required codec is:

Mpeg-1 layer 2 audio

that is supposed to come with your comp but i dont have it, where the hell can i find it, i didnt see it on this site

I TAKE IT YOU USED GSPOT TO FIND WHAT CODEC IS USE. ARE THEY MPG IF THEY ARE THEY SHOULD PLAY IN WMP

codec is missing? error message C00D100D1

can someone help?

kanno