Hi,
the question is not clear to me (with google translate),
but if your prefab doesn't appear, go to the area where you placed it, then press F1
in the console write dm (send)
then cr (enter)
you will see the prefab appear, but if it is not rotated correctly you will need to rotate it in the Wolrd Editor.
to exit "Debug mode" write dm again (send and Esc).