Scrap Heap Hero

When a hero has undergone a Heroic BSOD and the retirement is longer than ten minutes, maybe the hero failed altogether or just fell victim to their own personal demons. Whatever the reason for it the hero has been at best forgotten and is perhaps even actively despised or ridiculed, a has been or even worse a never was, but something happens and the Scrap Heap Hero rises first from the ashes and then to the occasion, showing everybody just what they once did or could have done had things gone differently.

Nearly always results in He's Back. Could overlap with Retired Badass, compare with Let's Get Dangerous.

Film

 * Herbie in Herbie Reloaded, a literal example, saved from the salvage yard, his previous racing career seemingly forgotten, his new owner less than thrilled by the vehicle circumstances have forced on her, then she's gets in a race and after a few false starts while Herbie gets the kinks out of it's system the car goes to show that there's plenty of life left in the silly looking race car yet, winning the race and his owners heart once she realizes what she has.
 * Russel Casse from Independence Day, an alcoholic ex-military pilot turned cropduster and UFO crazy, had zero respect from his step-son and even less from his neighbors. Still managed to join in the attack on the Mothership and after a few initial miscues manages to save the President, would have shot the missile that took down the ship if the firing mechanism hadn't failed - instead sacrificed himself by flying his plane directly into the main weapon and turned the course of the war.

Western Animation

 * The Easter Bunny Is Coming To Town has Chugs, another literal example, this time a train, the "runt of the roundhouse, everybody put him down. Yeah. He was really singing the blues." Cue Grief Song.

Literature

 * Jack Random from the Deathstalker books by Simon R Green, once a famous fighter against the tyranny of a corrupt empire he fell on hard times and was working as a janitor in a gym, sleeping in the back and subjuect to constatnt mockery and abuse form his boss. Then Owen Deathstalker showed up and gave him the figurative slap upside the head to shake him out of his misery and the Eternal Rebel was back.
 * The main character (The Coyote) and several others in In Hero Years, I'm Dead by Michael Stackpole. It's pretty much a major theme of the book.

Comics

 * Nite Owl from Watchmen fulfills this trope when he returns to active crimefighting.
 * Iron Man after he came back from being The Alcoholic and The Crazy Homeless. It was a long process that even had him using a modified version of his very first armor.
 * Bruce Wayne in Dark Knight Returns is a retired, out of shape alcoholic. He's been away from crime fighting for so long, the younger generation don't think he ever existed, despite the super villains being known to exist.

Video Games

 * Several companions from the Fallout series are this. Cassidy was an adventurer who developed a heart condition and became a barkeeper. His daughter was a hard-drinking caravan merchant who had her caravan destroyed. Raul was a vaquero turned mechanic. All three prove to be competent fighters when you recruit them and the latter can be inspired to go back to his vaquero ways.