“Have a Nice Day!” is a sentimental coming of age dramedy that doesn’t quite come off. Lots of promising if somewhat conventional possibilities are introduced, with only the least interesting of them pursued.

It’s lighthearted, but ungainly, incomplete and disappointing more often than not.

Álvaro Guerrero plays an aged ex-DJ forcibly retired a long way from where the action is. But back in the day, he was a star of Mexico City’s Universo Musical, famed for his introduction of “La hora de rock and roll,” on the radio.

Now Enrique Guerrero, aka “Enrique Guerrerock,” is just “‘Rique” to his equally-aged pals down at the town barbershop (Eduardo de la Peña, Fernando Larrañaga and Sidney Robote). They sit and sip Cuba Libres and tell ‘Rique stories when he’s not around.

But an announcement on the radio about an upcoming anniversary celebration kind of freaks ‘Rique out. Surely his old flame, the co-hostess, “La Bomba,” who dumped him when the station broke up their team years before, will be there. He’s still got his ancient Boss Mustang, although now it’s a wreck. He needs cash to fix up the car, clean himself up and make the trip to Mexico City to show her what she lost.

That’s how he winds up bagging groceries at the supermercado. And that throws him into conflict with the kid ordered to train him, Picho (Eduardo Minett).

‘Rique is revered by the manager, so he can do what he wants, smoke in the no-smoking zones. When he helps himself to more than his share of the tips, Picho is pissed. The kid’s got enough problems, pining away for his favorite cashier and high school classmate, Amanda (Andrea Chaparro). Cavalier ‘Rique is a bit of a cock-blocker, in that regard.

But that’s how the hustling, shortcutting, charming and shoplifting ‘Rique smooths things over with the kid. He’ll help him learn how to break out of the friend zone with Amanda, if Picho will help him in his latest side hustle — pilfering the recyclable cardboard from the store that pays their salaries.

The kid is treated to an Elvis pompadour — because that was “cool” to rock-a-billy loving ‘Rique. He learns to be mysterious, elusive and remote. And he is trained in how to steal and somehow get screwed out of part of his share as they make off with all that cardboard.

The romance is muted, both the budding new one and the one ‘Rique remembers from long ago in chaste flashbacks.

The workplace rivalry is seized and abandoned. Nostalgia takes over the picture, but the most colorful milieu and characters — the barbershop — are barely in it.

This plays as a star vehicle for the screen veteran Guerrero, with all these young folks (the singer Saak is cast as a love rival for Amanda, Mr. “Filet Mignon” from the meats dept.) stuffed in around him to make it palatable to a larger audience.

Nothing really comes off, little is taken to the point of completion and even less turns into something satisfying to sit through.

Rating: TV-MA, profanity, smoking, drinking

Cast: Álvaro Guerrero, Andrea Chaparro, Eduardo Minett, with Eduardo de la Peña, Fernando Larrañaga and Sidney Robote

Credits: Directed by Yibgran Asuad, scripted by Javier Peñalosa. A Netflix release.

Running time: 1:33