The Passive form of the sentence is - He said that he had tried everything without success.
Passive Voice refers to the formation of the sentence in such away in which the more emphasizes is given to the person or the object rather than performance of the action or the experience of the speaker.
The conversion of the sentence into passive voice the sentence formed is He said that he had tried everything without success.
Learn more about passive voice here:
https://brainly.com/question/85850
#SPJ1