All households and all house disapear after a new one created

EA/Maxis changed the way to add new households to a save. You are probably starting a new game each time.

To create a new household, load the save you want to add the household to and then click on the add new household button in the lower right corner of the map.

If you want to move over some of the families you've created in the new saves, use the load button to open those old saves and save the families to the library, then import them to your current game.