NEW YORK – 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 told The Associated Press.

Britney Ross of Rogers & Cowan declined to say Tuesday why Downey 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.

Downey, 43, has struggled often with drug abuse, but has also received much acclaim for his acting, including an Academy Award nomination for his starring role in “Chaplin” and strong reviews for his title performance in “Iron Man,” one of this year's biggest hits. He next will be seen in “Tropic Thunder,” along with Ben Stiller and Jack Black.