A question needs a question mark and an answer. If no answer is needed, it isn’t a question and it shouldn’t have a question mark.
No question mark after an indirect question.
- Why did he go home so early?
(direct question)
She didn’t know why he had gone home so early.
(indirect question) - Have you seen his new car yet?
He asked if I had seen his new car yet.
No question mark after a statement.
- Do you think she is happy?
(question)
I wonder if she is happy.
(statement) - Who taught you how to drive?
I’d like to know who taught you how to drive.
