I’ve been playing Halo: Reach for years now. Just last Friday i opened the game and it brought me to the menu that appears when you open the game for the first time. It’s really weird because my other games still have data. I opened Halo 3 and all of the stuff was still there. Even weirder is when i opened my achievements list it showed all of my achievements from Halo: Reach. I’ve tried restarting the console, deleting and re adding my account, let it sit for a day, tried it on my 360, but its still not there.
A hard reset of your console might work.