Please explain what is the difference between "what happened" and "what has happened?" I know that "has happened" indicates the action completed recently and "happened" refers to the action finished in the past, but I still doubt.
A: Hi, Carla. It's Jake.
B: Jake! I have not heard from you for two weeks. How are you?
A: Not very good actually.
B: Why what "has happened" or "what happened?"
Which one is possible here?
And one more thing:
A: I had an accident and I have broken my leg because I had forgotten to put my helmet on.
B: I hope you "have learnt your lesson" or "learnt your lesson".