Blueprint "Windows" (Viewport, Event graph, Conponents, etc...) desappeard


I have a problem with UE 4.20.1, I have load my project this morning, it was saved succesfully last night but when I want to edit one of my character BP (only this one) multiple “windows” disappeard. The viewport option and the others are not in the “window” tab so I can’t reoppen it, some toolbar options have been deleted too. I have already try to “reset layout…” without succes. I tried to add them manually without succes too. Create a new one work at the begining but after edit some things, compile, save then reoppen it the problem come back. I have try to use a backup version of this BP but the problem still there…

Can you please help me ? (Sorry for my bad English by th way) Thank you.