Question

please tell me who is your headmaster. - correct it

Answer 1

The given sentence should be written correctly as shown below:

Please tell me who your headmaster is.

Helping verb is usually put after the subject in statements, exclamations, and imperative sentences. Only in questions the helping verb precedes the subject.

In this case it is imperative sentence. So the helping verb (is) will come after subject 'headmaster'.

Answer 2

Please tell me who is your headmaster is?

Hope you need to correct the sentence, and if you want to ask the question about our headmaster then it is impossible to answer you because it is not the right place to showcase our school.

However, your sentence should be end with a question mark because here you are asking about something that you want to know about headmaster.