Sims 3 disappeared from library

I have played countless of hours of the sims 3 and had almost every single expansion. Since there was a sudden update from the sims 3 (that I did not install) my sims 3 has disappeared from my library. I did not do anything with the game because I was too scared to update it or play it. Now it says that I need to buy the Sims 3 (and all expansions) because I do not own them. This means all my hours of playing in the game and all my expansions thus my money is gone. Can anybody please help me? It is like my childhood has been erased.