Over the past dozen years of taping Two and a Half Men on Stage 26 on the Warner Bros. lot in Burbank, Calif., Jon Cryer had grown to dread the inevitable last-minute rewrites that would come his way. That is, until Feb. 6, when he wrapped his 262nd and final episode playing Alan Harper on the hit CBS comedy. "This time around, when we shot the very last scene, I kept hoping for rewrites because I just did not want it to end," Cryer explains. "I looked over to the bank of monitors that the writers sit in front of and they were all hugging. I knew that meant that they weren't doing any more rewrites, and that's when I started crying."

Cryer is not the only one shedding tears as another long-running broadcast sitcom rides off into the sunset. Two and a Half Men signs off on Feb. 19 after 12 enormously successful seasons (five as TV's top-rated comedy in total viewers), and just as the broadcast networks struggle (again) to find new hit comedies.

When Men debuted in 2003, it occupied one of 36 sitcom slots across the big four networks, in addition to another 16 on the since-merged WB and UPN—a lineup dotted with monster hits including Friends, Everybody Loves Raymond, Will & Grace, Frasier, The King of Queens and That '70s Show. Today, only 26 broadcast time slots are devoted to comedies, while the number of ratings juggernauts is down to just one—CBS' The Big Bang Theory, in its eighth season—with no clear heir to the sitcom throne in sight.

With CBS' How I Met Your Mother closing shop last year, Two and a Half Men wrapping this week, and Parks and Recreation—NBC's top-rated sitcom in adults 18-49, airing its series finale on Feb. 24—broadcast comedy is in a state of transition. While formidable comedy blocks remain on Sunday night on Fox (The Simpsons, Brooklyn Nine-Nine, Family Guy), Thursday on CBS (Big Bang, Mom, Men) and Wednesday on ABC (The Middle, The Goldbergs, Modern Family, Black-ish), sitcom ratings are down across the board, and this season is littered with failures: ABC's Manhattan Love Story and Selfie, NBC's A to Z and Bad Judge, Fox's Mulaney, and CBS' The McCarthys and The Millers (the latter last year's top-rated sitcom in 18-49 but canceled this season after just four episodes).

"The broadcast networks are confused, and understandably so," says Stephen Falk, creator of FX's comedy You're the Worst. "That naturally leads to maybe throwing things against the wall that maybe aren't of always the best quality. But when you see your ratings erode that much, you just have to try whatever."

Last month, NBC Entertainment chairman Robert Greenblatt waved the white flag during the Television Critics Association's Winter Press Tour, admitting, "We are really challenged by the comedy brand that we're trying to build on this network." Greenblatt made the historic decision to move sitcoms off the network's Thursday prime-time lineup for the first time in 35 years (RIP, Must-See TV) while offloading its promising midseason comedy, the Tina Fey-produced Unbreakable Kimmy Schmidt, to Netflix (where it premieres March 6). "I didn't want to put Tina's show on and have it fail because we couldn't launch it with the right lead-in," Greenblatt said.

Despite all the struggles, in conversations with network executives, showrunners, stars and media buyers, a surprising consensus emerges: There is still plenty of fight left in the sitcom. Comedy might not be the dominant broadcast force it was a decade ago, but it is still an essential part of the TV landscape and everyone remains optimistic that the next hit could happen as early as, well, this week.

All the networks are searching for their own version of what CBS has: a huge comedy hit in The Big Bang Theory, averaging a 4.6 rating in adults 18-49 this season and beating TV's second-place comedy, ABC's Modern Family, with a 3.4. (Those are the only two comedies to average better than a 3.0 this season.) Not only does Big Bang lift the net's entire Thursday lineup and bring millions of viewers to whichever show leads out at 8:30 (the most recent beneficiary being Mom), but when CBS aired Thursday Night Football in the fall, the network deployed Big Bang to Mondays to help fill the void left by How I Met Your Mother bowing out.

"Big Bang is a supernova of a show," says CBS Entertainment chairman Nina Tassler, citing the specificity of its voice and tone, unlike anything else on broadcast. "They're rock stars in originals and repeats." Case in point: When CBS pulled the low-rated The McCarthys from its lineup on Feb. 5, substituting a Big Bang repeat, ratings jumped by a third, from a 1.5 to a 2.0.

And Big Bang's influence reaches beyond broadcast. While the cable networks have found critical hits in the likes of Comedy Central's Key and Peele and Inside Amy Schumer, FX/FXX's It's Always Sunny in Philadelphia, Archer and You're the Worst, and HBO's Veep and Silicon Valley, ratings are another story. During multiple weeks this season, all 20 of basic cable's top 20 sitcom telecasts in 18-49 were, in fact, off-net episodes of Big Bang Theory on TBS.

To media buyers, it really doesn't matter where comedy runs. "From the advertising perspective, comedy can come from anywhere—it doesn't have to be broadcast," notes Dan Cohn, client director of investment at Initiative. "If based upon the pilot season, the broadcast networks have the best comedies in our opinion … we'll associate our brands accordingly. [If they] come from Comedy Central or FXX or TBS, we're happy to go there."

Patience is just as important a factor. As the public time-shifts its viewing, it initially gravitates to dramas over comedies. "Comedy lacks, just inherent in the storytelling form, the kind of urgency that the big dramas have, that create a tendency in the audience to watch in a quicker period of time, which is how we're being judged," says Dana Walden, co-chair and CEO of Fox. She cites New Girl, which jumps from 2.9 million total viewers in live-plus-same day to 6.3 million when 30 days of multiplatform viewing are factored in. "There is still a real appetite for comedy. It's just not being prioritized over, 'I want to see Empire or How to Get Away With Murder before the next episode comes on,'" she says. "As an industry, when we start appropriately evaluating the performance of all of these shows, comedy is still very much in there."

Tassler agrees. "Comedy is alive and well. It just sometimes takes a little longer for things to build," says the exec, pointing to Mom's ratings growth. Now in its second season, Mom had the benefit of a post-Big Bang time slot. Another of the net's comedies, Mike & Molly, quietly celebrated its 100th episode, meanwhile, and has become a prized utility player for CBS, coming off the bench each midseason to fill in for faltering fall entrants. "You get to this place where you know your fans will wait for you, and you know they're going to come back strong," says Mike & Molly star Billy Gardell. "And the network knows that, so they know they have a little room to try new stuff."

That is also why Tassler isn't panicking over losing another long-running sitcom in Men. "That's the nature of our business," she says. Tassler is hopeful, meanwhile, that midseason comedy The Odd Couple—which launches Feb. 19, and whose classic iteration on ABC in the '70s inspired so many sitcoms over the years—will buck the trend. (Matthew Perry's return to a multicamera, Thursday sitcom for the first time since NBC's long-running Friends wrapped in 2004 could be another plus—though his other post-Friends TV projects, NBC's Go On and Studio 60 on the Sunset Strip and ABC's Mr. Sunshine, stumbled. "I'm an eternal optimist," says Tassler.)

The Odd Couple's cushy, post-Big Bang slot could help it dodge a problem that has doomed many new sitcoms. While shows often need time to find their rhythm and voice, they tend to get yanked for failing to achieve immediate ratings. (Seinfeld and Cheers famously underdelivered out of the gate, only to eventually become audience favorites. "You're under this pressure to have that opening weekend. It's like movies, really," says Unbreakable Kimmy Schmidt co-creator Robert Carlock. He points out that few comedy pilots arrive fully formed, the exceptions being Modern Family and Frasier.

That makes an established comedy lineup all the more valuable to a fledgling entry. "Right now with broadcast, people are trained to know to go to certain places at certain times to look for a certain kind of show," says Mike Schur, exec producer of Fox's Brooklyn Nine-Nine, which enjoyed a ratings bump in Season 2 (it's already renewed for Season 3) when the network moved it from Tuesday to Sunday. "Fox has done a very good job of training people to know that on Sunday nights, there's comedy."

Meanwhile, sitcoms not fortunate enough to be in that position—especially those that end up on the bubble each year—are doing whatever they can to keep viewers engaged. "You have to be relevant, because if you're not getting the numbers you hope you get, it at least has to be the kind of show people are always talking about," says Mindy Kaling, creator and star of Fox's The Mindy Project. Kaling has certainly kept people talking this season, with an episode that skirted around a sex act not usually explored on broadcast TV and, more recently, with her character's surprise pregnancy. "I'm not trying to do an extra risqué show, but I do think that has helped us, that we are just in the zeitgeist," she says.

Since the network's beginnings in the '80s, Fox has been no stranger to taking risks with comedies, having green-lit such groundbreaking fare as Arrested Development, Married … With Children, In Living Color and The Tracey Ullman Show, which itself birthed The Simpsons. (To be fair, the net also broadcast such bombs as Stacked with Pam Anderson and Pauly Shore vehicle Pauly.) Coming up next at Fox: The Last Man on Earth, a futuristic comedy premiering March 1 starring Saturday Night Live alum Will Forte as the planet's sole inhabitant after a virus wipes out mankind. "There's so many options out there, and you're not just fighting against things that are cable or Internet channels, you're fighting against the catalog of everything that's ever been made that's available to you at any moment," says Last Man executive producer Chris Miller, who returns to TV after writing and directing, with partner Phil Lord, the feature films The Lego Movie, 21 Jump Street and 22 Jump Street.

Like Kaling, Miller stresses originality over formula. "To do something that's going to get people's attention," he says, "my theory is you have to do something that feels unique and special and gets people talking: 'Did you see this thing?' We wanted to do something that didn't feel like anything you've seen before, because otherwise, what's the point?"

As they await the fate of Last Man and other midseason entries this season, the networks are already looking ahead to next season. More than 40 comedy pilots have already been ordered by the big four. Even The CW is getting into the act, using its digital extension, CW Seed, to develop potential sitcoms for the drama-centric network. "The whole purpose of Seed was to basically use it as a comedy arm we didn't have," says network president Mark Pedowitz. "We knew our audience wanted to have some comedy."

"We'd love [the networks] to find the next Friends, the next Raymond," adds Initiative's Cohn. "We're eagerly awaiting the upcoming pilot season and the upcoming previews to the upfronts, and we're anticipating that they're going to hit home runs. It doesn't always work, but we're supportive and here with our clients to help try to find that next great comedic show."

Even if the genre is on shakier ground than when Two and a Half Men debuted, every network wants a shot at creating TV's next big comedy. That includes You're the Worst creator Stephen Falk, whose last broadcast series, NBC's Next Caller, starring Dane Cook, was picked up for 2012-13 midseason only to be abruptly canceled before any episodes aired.

While praised by critics (Slate called it the best show of summer 2014), You're the Worst has delivered only modest ratings. Still, FX renewed it for a second season, relocating it to offshoot FXX, which earned comedy cred last year by running every episode of The Simpsons in a 12-day marathon.

Despite the solid notices for You're the Worst, size still very much matters, Falk admits. "To have more eyeballs on your art—if I could call television 'art'—would be always a nice thing. I'd love 20 million people to watch You're the Worst."

Hollywood remains solidly confident that TV's next great comedy is just around the corner. "Television's a very cyclical business," points out Walden, noting that when she started at 20th Century Fox Television in 1992, the powers that be had decided dramas were done. Then, the studio developed The X-Files for Fox and Steven Bochco created NYPD Blue for ABC, and they were suddenly hot again. "You can't ever rule out a genre of storytelling," says Walden. "There's going to be another breakthrough comedy, and then we're going to say, 'Oh, comedy is back!'"