- last post: 01.01.0001 12:00 AM PDT
That happened to me too, I'll explain [as far as I know]:
When Bungie released the 2 new maps, Tombstone and Desolation, they released an update, if you didn't downloaded the maps, you were told to update anyways, or you wouldn't be able to play.
If you played Matchmaking after the update, all your stats and your rank were <deleted>, so you need to start from zero.
I was level 20 in snipers and rumble pit, now I'm 15 and going for more, and rumble pit is not ranked anymore.