I was going to rename an object by double clicking the name in my Outliner and accidentally pressed some keyboard combination. I don't know how many keys I pressed but they are all around the Enter key and now everything is expanded recursively.
I can click the minus sign on the outermost hierarchy to close them but inside them would be still expanded if I want to look inside again. I would like to know this key combination that expand all/collapse all so I can undo this. Doing it manually is not feasible because I organized the project by parenting. There are so many children.