Where in the World is Charlie Sheen?

— -- Earlier this year, it seemed nearly impossible to get Charlie Sheen to shut up.

He did a slew of media interviews, then took his act on the road, for his Torpedo of Truth tour. He broke a Twitter record, joining the social media site and quickly garnering over a million followers in one day and coining such phrases as "tiger blood" and "winning." And his antics -- filing a $100 million lawsuit against his former "Two and a Half Men" employers, breaking up with one of his live-in goddesses, and insulting his former co-star and two ex-wives -- kept him in the headlines.

So the silence coming from Sheen's camp now is almost deafening. Since completing his tour in May, Sheen has been mostly MIA.

Sheen's rep did not respond to requests for comment from ABCNews.com.

But a friend contacted by ABCNews.com said, "I've seen him and he's doing O.K.," refusing to elaborate any further.

Sheen will also be missing on this year's Emmy ballot.

After two opportunities to submit his name for consideration for his role on "Men," Sheen failed to do so by the May 25 drop-dead deadline, according to The Hollywood Reporter.

"It's up to the individual, whether they want to engage or not engage," Academy of Television Arts & Sciences chief John Shaffner told THR. "It was his choice."

Without his name on the official ballot, Sheen, a four-time nominee for "Men," has no chance of winning for the series, now that he's been fired and replaced by Ashton Kutcher. He's also unlikely to show up at this year's Emmy ceremony, clearing the way for host Jane Lynch to make all the Charlie Sheen jokes she wants -- though she may hold back since she's put her own name in for her guest role on "Men."

Sheen's former co-stars Jon Cryer, Angus T. Young and Holland Taylor also submitted themselves, but Warner Bros. did not submit the show for outstanding comedy series.

Cryer, whom Sheen dubbed a "troll" and "traitor," recently spoke to David Letterman about his former friend's quick downward spiral.

"It's as much a mystery to me as to everyone, I think," Cryer said Wednesday.

"I love him, he's a great friend," Cryer added. "None of us wanted to continue with the show if we felt like it was hurting him, and there was a point at which, we felt like, there's no control over him."

And now there seems to be few sightings of him. Sheen had been scheduled to take his tour to Australia and Europe this month, though there's been no word on the tour's status.

As for accompanying his friend Sean Penn to Haiti, as Sheen promised in March, Penn's rep told ABCNews.com, "The trip has not happened."

Sheen continues to update his Twitter account. In his most recent post a few days ago, he said he's nearing the final selection for a social media intern. "Tiger Blood Interns!!! the final 50 have made this a TOUGH decision... you're all amazing!!! decision soon... patience cadre... patience...," he wrote.

Meanwhile, ex-wife Brooke Mueller is generating her own headlines. Footage of the meltdown that led to Mueller's return to rehab last November aired on Paris Hilton's reality show "The World According to Paris" on Wednesday.

In tears, a desperate Mueller begged Hilton's mother, Kathy Hilton, to get her help.

"I'm having really bad cravings, really bad urges... I feel embarrassed... I feel like I'm going to do something stupid... I think I need to go back to rehab," she told Kathy.

The meltdown occurred hours after Paris Hilton took Mueller out on her first date since her split with Sheen. Hilton and her boyfriend Cy Waits set Mueller up on a double date with Marco Andretti, one of the heiress's friends. But a nervous Mueller cut out of the date early, and later that night returned to the Hilton mansion, where she broke down in front of Kathy.

Escorted by Hilton's mother, Mueller was shown entering a clean living facility last November. Mueller returned to rehab recently in April, just as her divorce from Sheen was being finalized.

The couple recently called another ceasefire in their custody battle over 2-year-old twins Bob and Max. Earlier this month, TMZ reported that they had reached a new deal giving them joint physical and legal custody, though Mueller will be the children's primary caregiver.