Battlefield 3 disappeared from my Origin

I had Battlefield 3 Premium but I haven't been on my PC to play in a couple months and now when I start Origin I dont have any games and when I put in my key code to reactivate like it says, it says my key code is already used.. I bought a brand new copy from walmart, I didnt even get a code by downloading the game from Origin or anything.. I don't understand whats going on..