What happened this is answer
How means
What (question word).
What happened (question word sentence).
Question word sentences are two types
1. Question word answer
2. Question word question
Examples
1. question word answer
What happened
QW V2
Where you are going
QW S HV V4
2. question word question
What did happen?
QW HV V1
Where are you going?
QW HV S V4
If helping verb is after Question Word means that is question.
If subject or verb is after Question Word means that is answer.
Question :
What did happen?
QW HV V1
Answer :
What happened
QW V2
English people are teaching wrongly. They did not know about language and meanings of the sentences.
