Hello,
When Halo: Reach came out, I bought the Legendary edition from Gamestop. I had gotten the codes for the Recon helmet and the flaming helmet appearance. I have not been playing for a while, and now they have disappeared from the armory. Does anyone have a similar experience or could someone tell me how to contact 343 Industries about it?
Thanks,
MattDar
Head over to the Xbox Dashboard
Go to Settings
Choose the Account box
Choose Download History
Look for Legendary Bonus Content & Standard Bonus Content, re-download them both.
They should now be back in-game.
It worked. Thank you so much. 
Sincerely,
MattDar