90s-00s YA Fantasy about teleportation where the reader must solve riddles to advance the plot

[Beth]

Asking for a friend, here’s his description:
“okay so all i remember is that it has a guy on the cover, kinda cute, black hair and he has on a white tshirt and blue jeans and he’s holding a torch. it’s like a YA fantasy book. like he gets teleported to another planet and he has to solve riddles to escape but the riddles are in the book for you to solve i think. From the 90s or 00s.”