Psychosomatic Superpower Outage

Super-powers are frequently linked to one's mental state. When the character has unresolved emotional issues, his or her superpowers can stop working. This is universally true of explicitly Psychoactive Powers, but this also can apply to powers that don't normally seem to have a psychoactive component.

Sometimes, there's really nothing wrong with the character's powers; he's just so out of emotional whack that he just can't bring himself to use them.

A Psychosomatic Superpower Outage is often precipitated by loss of self-confidence, loss of faith in one's cause, unresolved emotional conflict, a Freak-Out or extreme fear.

Anime and Manga

 * In Sailor Moon, Usagi loses the ability to use her Moon Tiara Action spell; it's because she subconsciously doesn't want to be Sailor Moon anymore.
 * When Guyver's Sho Fukamachi sees the damaged Guyver II consume its host, he has a Freak-Out and can't bring himself to bioboost.
 * In Episode 8 of the OAV, Guyver won't respond when Sho calls for it after realising that he had killed his father (who had been transformed into an Enzyme II) when the Guyver's autopilot had taken over after Sho himself suffered massive head trauma. Sho's extreme determination to save Mizuki several episodes later is what gets it working again.
 * During Tekkaman Blade, Blade goes into an Unstoppable Rage after exceeding his time limit. When he recovers, he goes into a Freak-Out and is so afraid that it will happen again that he can't transform.
 * During Ronin Warriors, Kento can't summon his Armor of Hardrock after Big Bad Talpa tells him (falsely) that the armor is inherently evil.
 * In Fairy Tail, this happens to Mirajane and Elfman after the latter tries a full-body Take Over, loses control of himself, and ends up killing their younger sister Lisanna. They're both left unable to use Take Over, because trying to use it reminded them of the incident.
 * Elfman could still use his. It's just weakened, and he prefers not to.
 * In Prétear,, The Reveal regarding the Princess of Disaster shakes Himeno so badly that she can't transform until she manages to recover her resolve with some support from Hayate in the following episode.
 * In My-HiME, a shocking event that greatly distresses Natsuki prevents her from using her powers late in the story. In the anime, it's learning that her mother, and she is unable to use her powers until she . In the manga, she loses her powers after learning from Nagi that Yuuichi kissed Mai, and gets them back while fighting , after an internal monologue about caring for Yuuichi in her own way.
 * In Puella Magi Madoka Magica, according to supplementary material Kyouko Sakura used to have the power to create illusionary clones of herself, but lost it.
 * This is the main conflict of Kiki's Delivery Service; the heroine loses her witch powers and goes through an identity crisis

Comic Books

 * Green Lantern: Kyle Rayner loses his powers when his confidence is shattered by Megaddon.

Film

 * During Spider-Man 2, Peter Parker loses his powers because he is unconsciously conflicted about whether or not to continue being Spider-Man.
 * This plot element may have been suggested by a similar plot point in 1964's Amazing Spider-Man Annual #1.

Literature

 * This happens to Tonks in Harry Potter and the Half-Blood Prince. She loses control of her metamorphmagus powers in her depression over both Sirius' death and her feelings for Lupin. We later learn that this also happened to Merope, when she was under the thumbs of her brother and father, and Dumbledore's sister Ariana after being attacked by a group of Muggle boys.

Live-Action TV

 * This also happens to the title character of Chuck.
 * John Locke of Lost loses his Island-restored ability to walk after an incident of self-doubt.

Video Games

 * Somewhat implied in Mass Effect 2. Your party members gain their final powers after you help resolve their emotional baggage.

Web Original

 * Hazard from the Global Guardians PBEM Universe is a super-athletic martial artist whose powers and abilities depend on the strength of his willpower. Normally, he's able to shrug off things that would completely disable normal people. If his confidence in himself is ever shaken, all his strengths and skills disappear.

Western Animation

 * After Zuko does his Heel Face Turn in Avatar: The Last Airbender, he loses his firebending powers for a while, since he no longer feels the anger (re: Emotional Drive) that fueled them.
 * The animated series Generator Rex features a hero whose powers flicker on and off depending on his feelings at the time.
 * On Teen Titans, Raven's powers stop working when the monsters in a horror movie they're watching come to life.
 * Starfire needs to feel happy to fly, so when she's depressed, she loses the ability to fly.