Trying to find a middle grade book about a boy finding his way back to his reality/universe after he's taken away from it

I don't remember much about the book but it's definitely middle grade and it's about this boy (might have worked at a bookshop/his family owned I'm not sure) and he's taken away from his universe/reality for some reason and then he finds other people that has this same problem and they all visit this multiple universes trying to find their way back home. Don't remember much about the middle but definitely remember the end where when he returns back home though he's still a pre-teen, his universe has gone through a century or something and he doesn't recognize it at first.

The Homeward Bounders by Diana Wynne Jones, I think. From the wiki article:

Twelve-year-old Jamie discovers a strange place in his hometown in which mysterious and demonic entities, known only as Them, are playing a board game with the entire world. Upon his discovering Them, They are forced to make Jamie a Homeward Bounder; this means he must constantly travel from world to world until he finds his home again.

Jamie awakens, alone, and realizes that Adam and Vanessa's world is his Home, only 100 years too late – he recognizes a photo of Adam and Vanessa's grandmother when she was young; it was his little sister, grown up. He realizes that although he did not age during his time on the Bounder circuits, time was still passing on his Home world, and his family and his Home world have gone forever.