@zitqhileAccording to ChatGTP:
This is an established science-fiction and fantasy premise, and there are several novels in which a person returns to an earlier point in their life while retaining the memories and knowledge of their older self.
The concept is often called time regression, life regression, or a second-chance time-travel story. The key distinction is that the character doesn't merely travel to the past in their adult body; they wake up in a younger body, with their adult mind and memories intact.
1. Replay — Ken Grimwood (1986)
A 43-year-old man dies and awakens in his 18-year-old body, remembering the next 25 years of his life. He uses that knowledge to make different choices, revisit relationships, and try to change his future. He repeatedly relives his life.
2. The First Fifteen Lives of Harry August — Claire North (2014)
Harry is repeatedly reborn at the beginning of his own life, retaining the knowledge he acquired in previous lifetimes. Unlike Replay, he returns to infancy rather than waking up as a teenager.
3. The Strange Life of Ivan Osokin — P. D. Ouspensky (1915)
Ivan is given the opportunity to return to his childhood and live his life over. He remembers what happened before, but discovers that knowing his mistakes doesn't necessarily mean he can avoid repeating them.
What if the character enters someone else's younger body?
That is also a variation of the premise, although it differs slightly from returning to one's own body. In fantasy and speculative fiction, related concepts include reincarnation with retained memories, body transmigration, and possession of a younger self or another person.
1. Once in Every Life — Kristin Hannah (1992)
This is a particularly close match. Tess Gregory, a modern-day research scientist, dies and begins a new life in post–Civil War America in the body of Amarylis Rafferty, a woman who is already a wife and mother. Tess retains her own knowledge and memories.
2. The Star Kings — Edmond Hamilton (1949)
John Gordon, a twentieth-century man, has his consciousness transferred into the body of Prince Zarth Arn in the distant future. He retains his own identity and memories while inhabiting another person's body. (this one travels to the future rather than the past)
3. Calculated Risk — Charles Eric Maine (1960)
This novel explores a form of psychological time travel in which a person's mind can be sent through time to take over another person's brain and body.