I've never had the food replicator not appear in the family inventory when I got one, and I've purchased lots of them. You're sure you checked the family inventory - the one you access through Buy Mode? Not your Sim's personal inventory? If it's definitely not there, I would think you've got a bug. And a nasty one, to lose a valuable item like that. There have been reports of things disappearing from inventories, but I think that was usually when people had been travelling. I don't remember hearing of a food replicator never showing up. Maybe someone else will have experience with this.
And welcome to the forum, Grannyjoy!