A limp reverse retread of "Big," "17 Again" not only follows in the wake of that classic 1988 Tom Hanks film, but also pales in comparison to more recent body- and age-switching comedies such as 2003's "Freaky Friday" and 2004's "13 Going on 30." As written by Jason Filardi (2003's "Bringing Down the House") and directed by Burr Steers (who impressed with his 2002 feature debut, "Igby Goes Down"), the picture is all over the map, a heartrending drama about divorce, a morality tale about severed ties between a father and his children, a slapstick farce full of gags involving light-saber battles and "Lord of the Rings" fanaticism, and a thoroughly disposable teen flick all rolled into one. None of the above really work, the intermittent well-meaning material getting lost in a mishmash of poor comic timing, treacly emotions, and broad caricatures posing as human beings.

Twenty years ago, hotshot high school basketball star Mike O'Donnell (Zac Efron) threw away the dreams he had for his future in order to support girlfriend Scarlett (Allison Miller) when she revealed to him she was pregnant. Now an unhappy thirty-seven, Mike (Matthew Perry) hates his job at a youth-centric pharmaceutical company, struggles to connect with teen children Alex (Sterling Knight) and Maggie (Michelle Trachtenberg), and is going through a rocky divorce with Scarlett (Leslie Mann). After a run-in with a magical janitor (Brian Doyle-Murray) and a fall off a bridge into a swirling vortex, Mike wakes to discover that he once again looks like his 17-year-old self. Deciding that the root of all his troubles as an adult can be traced back to the regrets of his past, he enrolls back into high school, tries to befriend his children while learning more than he ever wanted to know about them, and begins to fall in love all over again with Scarlett. Naturally, she is struck by Mike's resemblance to her soon-to-be ex-husband—a fact that makes it increasingly difficult for her to not cross the lawful boundaries between adult and minor.

Due to its unimaginative premise and pedestrian treatment, "17 Again" comes off as one thing only: a flimsy star vehicle for Zac Efron (2007's "Hairspray"). Efron claims he wants to take his career seriously and move away from his Disney-fied "High School Musical" image, but within the movie's first scene he is up to his old tricks, dribbling around a basketball and performing a dance number with surrounding cheerleaders. His body, toned and ripped to look like a Greek Adonis rather than a teenager—Efron is twenty-one in real life—is also gratuitously flaunted in the opening minutes, second in exploitation only to the film's disgusting portrayal of adolescent girls as either mindless whores or needy virgins just waiting to chase their preferred mate around the bedroom while growling like a tigress. The adult women aren't much better depicted, most of them called upon to act like humorless shrews. The movie's male component, come to think of it, are also less than attractive, falling into two categories: thick-necked, brainless bullies and socially inept dorks. Mike is the exception, but not a terribly likable one due to Zac Efron's reliance on striking oh-so-cool poses in every scene rather than wearing the shoes of his downtrodden protagonist.

With the characters a botch job of underdevelopment, director Burr Steer flounders by not spending enough time with any of his subjects and their subplots to make an impression. Mike's physically grown, maturity-stunted friend, Ned (Thomas Lennon), is a millionaire sci-fi geek whose attempts to woo Principal Jane Masterson (Melora Hardin) are so off-the-wall that there's no warming to his weird tactics. The payoff to these unfunny scenes is, surprisingly, funny (it's just about the only thing that is), but also so ridiculous that there continues to be an emotional disconnect. Mike's burgeoning relationship with Scarlett while in his 17-year-old body goes down a predictable path, though the thought of these two doing the deed isn't nearly as queasy as Maggie getting the hots for Mike, unaware that he is her father. Without crossing a line that the PG-13 rating would definitely not withstand, this storyline goes nowhere, is creepy rather than comical, and has no decipherable outcome.

As for adult Mike's troubles in connecting with Maggie and Alex, it is tossed away by the end and doesn't so much as feature one concluding scene between them. It's just as well, since Maggie is written with all the clarity of a smudged phone number written in lipstick. It is established that she is a good student, but then why is she still in high school when she has to at least be 19 years old (Scarlett got pregnant with her twenty years before)? And, for that matter, why is she so cheerfully going out with the biggest bully in school, Stan (Hunter Parrish), when his main mission is to terrorize Maggie's younger brother? That this is never brought up, and that Maggie and Alex do not share so much as one word with each other throughout the running time, is inexcusably neglectful.

"17 Again" is clunky and inept, a bad version of an ages-old premise that nevertheless has a lot of room for invention and creativity. The supernatural janitor who gets the plot rolling is written with such artifice that the viewer can't help but laugh at his very appearance. When humor is intentional, however, the safe bet is that it is going to fall flat or overstay its welcome. Zac Efron fails to impress with his first major headlining role—Matthew Perry (2004's "The Whole Ten Yards") plays the older version of Mike with more depth and less screen time—while game supporting performances from Leslie Mann (2008's "Drillbit Taylor"), Michelle Trachtenberg (2006's "Black Christmas") and Thomas Lennon (2009's "I Love You, Man") are wasted on a tone-deaf, half-written script that does them no favors. Even the forgettable soundtrack chosen here—usually the one reliable element of the teen genre—isn't up to snuff. In bringing "17 Again" to fruition, director Burr Steers should have added some extra doses of charm and realism to the equation. Instead, he's made a fantasy about a high school where few classes are taken, tests are a figment of one's imagination, and the students, all of them stock exaggerations, roam the hallways without a thought in their puny minds. Through it all, Mike's biggest apparent education is on twenty-first century fashion. As for his wife and ungrateful kids, well, let's just hope he doesn't piss them off a second time around.