Can't play a game I own??

I installed Crysis 2 a while ago, played it once or twice then forgot I had it. Upon coming back and trying to play, I'm just sent in a circle of errors nothing seems to fix.

It is installed. I own it. I have played it. (On this account!) According to EA, I no longer own it and need to sign in with another account. But I do not have another account. I have the product key- trying to put that in just tells me I have no internet. Except I most certainly have internet.

So ????? what do I do here? Please help, because I refuse to just buy it again. EA help is somehow of no help, and I'm out of ideas.