Well, As a first contribution I will try to help yas a bit ;
If you are having trouble with your time played ( Hacked, Stat Created, Messed up Something, De-Synced your playing time from your steam playing time, Or Whatever, )
You can just use any GOOD trainer ( MW2 MegaUnlocker, iJustHelp's One, ), And enter your playing time ( IN SECONDS ), Calculator is your friend if yas don't like maths.
Hope this helped you a bit, Just use the search function for the trainers =^-^=
iJustHelp's 1.0.180 Trainer =D
These two are great in my opinion, And it's easy to lean how to use them, Happy Hacking