Please describe it in a little more detail. Were they transferred to your console and have now disappeared, or how can you tell that they have gone missing?
If the DLCs have simply disappeared, there are two options you can consider: First of all, I would suggest simply downloading them again if you haven't already. If that doesn't help, it would be best to find out what really happened. You can check which DLCs are installed on your console by checking two things: the installation log and the memory used. The latter will give you a detailed list of all installed DLCs, just don't select any for deletion. If the DLCs are installed but not selectable in the game, that's a completely different problem. In this case, renewing the licenses may actually help.
