hey i currently have the 2 map packs and coldstorage but for some reason i cant play dlc wtf should i do?
maybe bungie hates you and does not want you play dlc (lol) jk try it again you 360 or halo 3 disc could have messed up. if it does not work after you have tried it about 3 times then idk.
Try resetting your cache by Going to the Xbox Dashboard, select the System Blade, and select Memory. Highlight the HD symbol and press Y. Press X, X, Left Bumper, Right Bumper, X, X. Note this procedure will reset autoupdates, and should allow you to play DLC after you redownload them. Other than that nothing will be changed on your Xbox.
Go to the marketplace and re-download the maps, It only takes about 10 seconds. Go into halo, Now select a DLC map and it should work. This has also happened to me more than once and this is what I done. I hope this helps.
try going into the forge lobby and loading your mapd before going into matchmaking next time you need help try to explain in more detail