Counter Strike Source not showing up in STEAM?

I havent played my Counter Strike Source in years, just dug it out to play it and downloaded all four cd's and now when steam comes up it doesnt show any games in my library? I never was asked to enter my product code (which ive lost) so i dont know if this is why or maybe i need to reinstall it? I figure this is such a popular game still someone has to know the answer! Thanks.