Change the narration: "I’ve forgotten to bring my lunch with me," he said.

He did inform that he had forgotten to bring his lunch.

He said that he had forgotten to bring his lunch with him.

He said he had forgot his lunch to bring.

None of these

He said that he had forgotten to bring his lunch with him.

Direct speech: "I’ve forgotten..." (present perfect)

Indirect speech: changes to past perfect → "he had forgotten..."

Pronoun "my" changes to "his".