I was bored, so I did it for you.
I know what you’re saying, my gamer tag is logged in, but when I turn the game on it brings up a side thing that says Player 1 Choose a save device (don’t know if that’s exact but yeah). Then I go to Xbox Dashboard, and sign out and back in; it doesn’t work. It’s never done this until last night. If you can think of anyway to fix that other than saying to log in and out or to log my gamer tag in (because it is) let me know, or tell me what you would do to get the game to recognize my gamer tag again because I can't figure it out.
Alright, so you're telling me that you signed onto your player profile, then signed onto your X-Box Live account from the game? You're not going to be able to get your saved games that way because the X-Box 360 recognizes a gamer tag as a separate profile, even though you can sign onto a Live account from any player profile. So, you need to set your X-Box Live account to auto sign-in, and stop using the player profile. That way, you always use your Live account, and you always get your saves and achievements from that one account. You have no need for a player profile when you have an X-Box Live account, as it treats the account as a separate profile that you can log onto.
From what I can deduce, you signed onto the Live account profile, and not your player profile. The game saves are on the account for the Live profile, and not your player profile. Delete the player profile, only use the Live account as your profile, and life is good.