I think there is only one way that is pretty sure to work. One by one, empty each room of every object. You'll need an empty room or a large clear area to stage removed objects. An alternative to this, though less reliable is to picture each room as a grid. Work methodically through the grid, ...

This may seem very silly but call for it. There have been studies that show calling for an inanimate object makes it easier to find. Other than that do a fingertip search, work from one end of the search surface and then work in a methodical way. For cupboards and draws, once searched put a pos...