I asked her if she knew anything about what had happened.
I want to know everything about what has happened here.
She knows a little about what happened but not much.
How much did he know about what had happened to her?
All the same, I'd like to know a lot more about what happened.
It does not tell us everything we need to know about what happened.
Maybe he knew something about what had happened that she didn't.
Okay, so you don't know a thing about what might have happened, or whether anything did happen.
However, once again, we need to know something about how this happened.
"He would like to know more about what happened before that night."