Here are a few possibilities for what you're looking for:
* The "Harry Potter and the Cursed Child" play: This is an official sequel to the Harry Potter series, written by Jack Thorne based on a story by J.K. Rowling. It tells the story of Harry's son, Albus Severus Potter, and features a new generation of wizards and witches.
* "Harry Potter and the Half-Blood Prince" by J.K. Rowling: While not technically a retelling, it's the sixth book in the series and expands on some events from the previous books, including the story of Half-Blood Prince's Potions book.
* Fanfiction: Many fans have written their own retellings of the Harry Potter story. These can range from slight alterations to major changes to the characters and plot.
If you can provide more context about the retelling you're interested in, I can help you find more information. For example, do you know the author or the title of the book?