Lost expansion packs

I purchased expansion pack "Cats & Dogs" last year and it played well for a while.  I logged in recently after not playing for a while and the expansion pack is no longer part of the game.  The saved games are missing the pets I adopted and missing pet related items in the yard. I have several saved games and they show the pet icon on the game but there is a message saying that a restart is required.  I'm afraid if I restart those game they will lose the expansion pack and the pet related data in the game.  Please help restore the expansion pack and the game related data.