I own the game yet I can't up date

I have  bought  this game and have been playing it. I play this game a lot when I'm in the hospital  recovering from brain surgeries  ( 5 if you'd like to know) I've been getting them for years and I had no problem and I  appreciate that. Now  I have been trying to play with my  cousins but now the game will not let me update says I don't own it. NOW HOW CAN I NOT OWN IT. I bought I before my brain  surgery's then I went throw my brain surgery's  with this game. Now I'd like to play this game and have it up dated if I could get some help that would be great