I remember that was an issue with NBA 2K13 when you needed to reinstall the game, so it could be an issue with NBA 2K14 too (I decided to go digital after all the trouble I had getting a new key for 2K13).
Basically, the only option that doesn't involve piracy (and thus the only option we'll be discussing here in the NLSC Forum

) is to contact 2K Support and get them to issue you with a new key.