Question

you said to him where have you kept my book​

Answer 1

Answer:

Indirect Speech: He asked me where had I kept his book.

Reason for the Tense Change

If you notice, the tense has been changed from the simple past (did keep) to the past perfect (had kept). This is an essential rule of speech conversion. When you put a sentence of direct speech into indirect speech, you go one step further into the past, because the question itself was asked in the past.

Answer 2

i said to him whers have you kept my book