Downey Jr. won’t pen book

The “Iron Man” will not be wielding a pen: Robert Downey Jr. has postponed plans to write a memoir and has returned his advance to publisher HarperCollins, a spokeswoman for the actor said.

Britney Ross of Rogers & Cowan declined to say Tuesday why Downey, 43, wouldn’t be writing the book, originally scheduled to come out this year. HarperCollins had billed it as a “candid look at the highs and lows of his life and career” when the publisher announced the project two years ago.