Taking it all with a grain of salt, there's lots of ways a key can be obtained via internet, lax stores' security, IT warehouses' workers, you name it. So it'd be interesting to know the whole story, maybe the user has accidentally destroyed the discs, while retaining the cd key; it's a possibility, but oh well.
And then, suggesting downloads of a pirated game, that's condoning piracy in itself, no matter what happened, and how the poster got his cd key.
Now a solution would be contacting the game's publisher/developer and take it with their customer service and see if they can get you a replacement copy, based on your actual cd key.