Guessing all the hacking may have caused problems.
If you get no where, google it and if nothing there just contact steam support/activion or cod support (if they even have one) and say you prestiged, then it reset your score etc and now you cannot do anything.
It's honestly difficult today, but if it happened after the update, some of your values could have scrambled and corrupted the game somehow... it's a longshot, but judging from that message, I can't see what else that'd be .-.
Verify local game cache through steam. If that doesnt work contact the relevant support centers. Apparently in the latest update they moved all the profiling online, so if you mess with your stats you run the risk of them not syncing up with the server :/
As the eagle was killed by the arrow winged with his own feather... We often give our enemies the means to destroy us.
If I helped at all, be a pal and hit thanks And a little rep goes along way!