Based on a typically heart-wrenching case study by Oliver Sacks, this admirably modest adaptation tells the story of Gabriel Sawyer (Lou Taylor Pucci), a homeless hippie whose burnout isn’t the product of drug abuse but a ballooning benign tumor that’s erased his memory. Institutionalized in the mid-1980s and rejoined with the suburban New York parents (J.K. Simmons and Cara Seymour) he’d long ago abandoned, Gabriel seems hopelessly locked in until a neurologist (Julia Ormond) discovers that his brain comes alive through the rock music of his youth. With a script tailored for a different budget and era and a scattershot, also-ran cast, The Music Never Stopped is clearly the compromised product of a decade-plus in development hell. But where star-filled Oscar-bait would have sensationalized Gabriel’s story, leaning on the horn with prolonged reaction shots, escalating strings, and performances bellowed for the cheap seats, Jim Kohlberg’s workmanlike directorial debut is better for its restraint. A teary finale pegged to the Grateful Dead’s “Touch of Gray” works precisely because of its odd, unforced specificity. But strain is evident elsewhere. In a rare leading role, character actor Simmons is saddled with the entirety of the film’s diagrammatic emotional arc, briskly (and tediously) about-facing on matters of fatherhood, activism, and guitar rock, while a too-boyish Pucci is fatally unconvincing as a former band leader. Whenever the music starts, he ensures that all plausibility stops.