As anyone who is familiar with Harry Potter knows, a horcrux is made when someone commits murder and stores a piece of their soul in something. Would it be possible for this someone to later recover and reintegrate their soul piece(s), should they want to?
Supposedly, yes - via full remorse...
From Deathly Hallows:
Ron: "Isn’t there any way of putting yourself back together?"
Hermione: "Yes, but it would be excruciatingly painful."
Harry: "Why? How do you it?"
Hermione: "Remorse. You’ve got to really feel what you’ve done. There’s a footnote. Apparently the pain of it can destroy you. I can’t see Voldemort attempting it somehow, can you?"
To the best of my knowledge, there's no canon example of anyone actually succeeding in this.