One thing you might be able to do is to place a chest back in the original spot, then build a ladder against the chest that would allow your Hearthling to reach it.
Another thing that might work would involve using the console commands (crtl-c) selecting the door and using the (teleport) command to place it on the ground.
I’m going to mark this as #not_a_bug. placed items aren’t affected by gravity, so it is possible to make them float by removing objects beneath them. @Geokhan’s suggestion to place a ladder is likely the easier without touching the console.
ok i am sorry if it is not a bug but i am quite new on the forum and on the game too. it is just when i select the door i have no action avalaible, and i can’t find the building it belong to. I gonna search for the console commands in the game. thank you very much for the help