Haise fought him (he's actually a her, I think). During this fight, Eto (the one eyed owl) shows up. While fighting Kanae with Eto watching, Haise ceased to be and Kaneki regained all his memories.
In Season 3, Kaneki lost his memories. Fandom. He got amnesia after losing the fight against Arima at the end of Tokyo ghoul. He got stabbed in both eyes and through the brain.
Eh, sort of. After the fight with the One-Eyed Owl, Haise accepted he was living in someone else's body. He now knew the life he had known was a lie, orchestrated by the manipulation of Arima. The new Haise we see after the fight is still Haise, but with Kaneki's memory.
The short answer : Yes. The long answer: He regained his memories from "Ken Kaneki" inside his own head. Therefore becoming Ken Kaneki again. Yes but he now retains memory from both personality, i.e Kaneki as well as Haise.
Did Haise Sasaki become Kaneki Ken again in episode 12 of Tokyo Ghoul:re? - Quora. Yep, he bloody did.
Rowling said in an interview that Dumbledore was about 150 years old. However, on her website, she states that Dumbledore was born in 1881, making him either 115 or 116 at the time of his death.
10 Elena Gilbert/ Nina Dobrev: 32, Dating, 5'5'', Capricorn. Nina Dobrev started filming The Vampire Diaries at just 20 but is now a grown 32-year-old woman. Since her departure on the series, she has branched out into feature films, appearing in many big titles such as XXX: Return Of Xander Cage.
10 Elena Gilbert/ Nina Dobrev: 32, Dating, 5'5'', Capricorn. Nina Dobrev started filming The Vampire Diaries at just 20 but is now a grown 32-year-old woman.