Question

one must do one's duty change into passive​

Answer 1

Answer:   “One’s duty should be done by one.”

Explanation:

This way (alone) will you convey the complete meaning of the original sentence in active voice, without leaving ambiguity in, both ‘whose duty’ is to be done, and done ‘by whom’.

Even if the use of ‘one’, twice, is avoidable, one can not help addressing its such use in the question.