[excellency]

Hi everybody,
I have a problem with this sentece because as long as I know

when we say:"I don't know where she was?" the subject and the verb change their own places. but what about this:"I don't know what is happening?"anyway, is it correct or not?please help me, thanks all in advance. And sth else,we say:"is it correct or not?" or "is it correct or no?"which one is correct?
thank you again.

[bread_baker]

Here's an answer for correct American English.
These are statements, not questions.
"I don't know what is happening."
"I don't know where she was."

This is a question, not a statement.
"Is it correct, or not?"

In American English, the grammatical rules for statements and questions are different.

[susan53]

As bread Baker said, because the sentences are statements, not questions, they follow subject - verb phrase order - so : I don't know where she was and not the question form Where was she?

But in the second sentence What is itself the subject of the verb. So this time the order doesn't change whether it's a statement or a question :
I don't know what is happening.
What is happening?

If it's this which isn't clear, see the thread Inversion in questions