Right well I got onto Halo 3 to play some campaign (from the first mission: Arrival), I went to go put on a few skulls but they had all disappeared. Then I noticed that my armour, emblem and tag had all changed(luckily all of the armour I'd unlocked was still there). I tried to change the campaign mission but they had all disappeared except for the very first mission. Naturally I'm very upset(I'd completed the game on legendary!). Is there anyway I could mod a save file to unlock all of the skulls, missions etc?