The Sims (Original/First Game)

Hi there.

A few years ago I got a sims game from my cousin. I lost the case and stored it safetly in another case. To log onto the game, I need a serial code which I don't have - I have lost it. How can I get a new serial code? Or at least play the game without one? I have been waiting to play it for a while now, and am gutted that I can't play it. 

From, Aniston