If the unit is locked down... and in a wrong area... you can single click the item (as the house owner OR the one that locked it down) and select retrieve. The item will pop in to your backpack.
I dont even "I wish to unlock this" for that option. Love it!
And yes… decorating... sometimes things go outside your reach and this is the best way to get them back.
OR, if the item is NOT locked down and unreachable... and a custom house, I "believe" it still works... where you can change house foundations (for a moment) and anything not locked down will pop out by the house sign. At least, this used to work. A good way to "shake the house", insuring everything was locked down. If I had my way, it would just be an option on the house sign vs. messing with the foundation.