HELP ME PLEASE!

ok ive had this game for about 2 days, i just tried playing it, and it said your stats have been reset. then i went to go into a game and it said key code is not valid. please enter your key code in the multiplayer options/enter key code menu and then try connecting to the server again.

Please help me!
How do i get my key code back cos when i go on to it its not there. and i dont know the key code?

Well if you dno the key, you are screwed.

is there anything i could do? like reinstall the game?