lost households

bethsinc_xx​  As said, the Slot_ file is a save.  Tray files do normally start with 0x0000, so if you're seeing that, it's normal; just put the files directly inside Tray.

"Local" in this context means stored locally on your computer, not remotely in some cloud storage service.

A factory reset would delete everything you might otherwise be able to recover.  So unless you want to lose everything, skip the factory reset; just put any Slot_ files in saves and any 0x0000 files in Tray, and see what shows up in the game.

For the worlds that don't load, let me know whether a new save is affected.  This problem has several causes, some of which are limited to one affected save.