It looks like some people are having their save games corrupted due to a bug in Call of Duty 2 and thus having to start all over from the very beginning. The corruption usually occurs after the African tank level in the British campaign, Ridge 88 has two strange workarounds. One involves logging into your profile before you start the game. The other is to cheat, and so Activision has released the mission select code to help people get back to where they were, atleast until a fix can be found.
At the mission selection screen, hold LB + RB and quickly press D-pad Left(x2), D-pad Right(x2), Y(x2).