Some TV networks have announced that they have given the green light to renew, restart or retool series.

First off, “NCIS’ ” Mark Harmon will be sticking around, and his hit CBS drama is returning next season.

The network announced Harmon’s one-year contract extension along with the renewal of a show that just keeps getting bigger. Now in its 10th season, “NCIS” for the first time ranks as TV’s most-watched program, CBS said. “NCIS” logs an average 21.5 million viewers each week.

Harmon’s Leroy Jethro Gibbs heads a team that investigates crimes involving Navy and Marine Corps personnel. The cast also includes Michael Weatherly, Pauley Perrette, Cote de Pablo, Rocky Carroll and David McCallum. “NCIS” premiered in 2003.

Starts and renewals

For many fans, the sound of moaning zombies is music to their ears. Yes, “The Walking Dead” (9 p.m. Sunday, AMC) is back to resume its gripping third season. The action picks right up from where it left off in December with reunited brothers Merle (Michael Rooker) and Daryl (Norman Reedus) locked in a fight-to-the-death orchestrated by the angry governor (David Morrissey). And the bloody battle in Woodbury has left nerves frayed and tensions simmering among a fragmented band of gutsy survivors.

CBS’ veteran comedy “How I Met Your Mother” will return next season, and it will be the final one for the series. And patient viewers of the long-running comedy will finally learn the identity of the enigmatic mother in the title. The series premiered in 2005.

Meanwhile, get ready for more “Girls.” HBO’s controversial but critically lauded, award-winning show will return for a third season. Star Lena Dunham said, “We’re starting season three at the end of March. I’m so excited.” Dunham also said she has a six-year contract with HBO, so there may be lots more “Girls” to come. The second season premiered Jan. 13.

And AMC’s acclaimed “Mad Men” will return for its new season April 7. The two-hour premiere kicks off the drama’s sixth installment.

Several cable series are getting new seasons.

Five series that are continuing on are Showtime’s “Shameless,” “House of Lies” and “Californication”; BBC America’s “Ripper Street” and Cinemax’s “Banshee.”

“Ripper Street’s” second season will debut in 2014.

“Shameless” just began its third season on Showtime. “House of Lies” recently began its second season. Star Don Cheadle won the Golden Globe for actor in a comedy series for “House of Lies.”

Matt Damon will guest star Sunday on “House of Lies” as a “maniacal megastar.” Damon plays opposite Cheadle, his castmate in the “Ocean’s Eleven” franchise.

MTV says its reality show “Buckwild” about some wild young West Virginians will be picked up for a second season.

The show has drawn criticism for what some see as a negative portrayal of the state’s young people.

Second chances

Fox’s “The Mindy Project,” with creator Mindy Kaling, has done a cast reshuffle, eliminating characters with little to do and elevating roles that appear to be clicking.

“Up All Night,” starring Maya Rudolph, Will Arnett and Christina Applegate, is on hiatus, which usually translates into “Dead Show Walking.” Instead, the series is expected to return in April to NBC with major changes, including a plan to film with multiple cameras and a live audience.

NBC’s “Smash,” last year’s heavily promoted musical comedy, has returned. Out is Uma Thurman; in is red-hot Jennifer Hudson. Out are solid relationships; in is an endless stream of hot, single Broadway babies.

Why this string of second chances? Four words: “The Big Bang Theory.”

That show was conceived as a sitcom about two physicists who befriend a fetching new girl. She proceeds to take advantage of their naive ways and cons her way into their apartment. CBS passed on this version, but continued to develop it with creators Chuck Lorre and Bill Prady for two years. The female character was reshaped and recast, leading to one of the most successful programs on TV today.

Networks have to be looking at that boffo scenario and believing that sometimes tinkering instead of tanking is the way to go.