Probleme scene :(

Hi everybody,

i 've got a problem with my scene and i don’t know what going on … i was working on a basic scene (interior apartment) everything was good and i dont know why, i restarted unreal … and reloaded my apartment and everything is transparent.
the skylight, camera, spherereflection … it’s like we did a scale on the “Z axis” … i can not see anything.
do you have a idea ?
thank you.
Here is a screenshot of what i’ve got.