Subjects:

Theory:

https://learnenglishteens.britishcouncil.org/grammar-vocabulary/grammar-videos/reported-speech

You need to be careful when working with questions in REPORTED SPEECH.
If the question can have a yes or no answer, you need to add IF
- "Do you like salad?" You could answer YES or NO.
- He asked me IF I liked salad.

"Where is the park?" only has one answer, so no IF is needed.
- He asked me where the park was.

The one step back in the past rule is needed for questions as well.
"Where IS the park?" becomes He asked me where the park WAS.
- Where IS my key?
- He asked me where his key WAS.

The pronouns are also changed with questions.
MY key becomes HIS key.
- Where is MY key?
- He asked me where HIS key was.

The important thing to notice is that the structure of the question changes.

WHERE WAS MY KEY? is the normal structure for a question.
MY KEY WAS is the structure of a positive sentence.
This is the structure used in a question in REPORTED SPEECH, because the HE ASKED ME takes on the role of the question, and NO QUESTION MARK is needed.
- Where is MY key? (normal question structure.)
- He asked me where (question structure) HIS key was.(normal sentence structure.)
- He asked me where was his key. (is not correct.)
- He asked me where his key WAS. (is correct.)

The same thing happens with YES/NO questions.
- Do you like football?
- He asked me if (normal question structure) I liked football.(normal sentence structure, and no question mark.)

These concepts are very common in PET sentence transformations.