SAN FRANCISCO — All but eclipsed by Facebook and Twitter, Myspace is aiming for a comeback.

The onetime king of social networking plans to revamp its Web site beginning on Wednesday, narrowing its focus on entertainment for people 13 to 35 years of age, also known as Generation Y.

“Over time, Myspace got very broad and lost focus of what its members were using it for,” Michael Jones, the president of Myspace, a unit of Rupert Murdoch’s News Corporation, said in an interview.

Mr. Jones said the more than 120 million Myspace members were primarily using the site to listen to music and share opinions and information about that music, as well as about movies and television shows. The new site will emphasize that content with a simplified service that removes much of the clutter that Myspace was known for, Mr. Jones said.

And Mr. Jones said Myspace would no longer seek to compete with Facebook, but rather to complement it. “Our focus is social entertainment,” he said. “Niche players have long staying power.”