My 12yo ds disliked reading until he found books he liked. For awhile, I would read aloud to him and he followed along in his own copy. Thankfully, our library has more than one copy of great books.
It really needs to be books that they want to read. After reading "junk" for awhile, it gets exhausting and they will crave something more stimulating.
Maybe try joining a book club, where the kids get to pick the book all the others pick... with minimal rules. We allowed comics, picture books, chapter books, etc. in our book club.
My son found The Ranger's Apprentice Series, Guardians of Ga'Hoole, and the Warriors series that way. All GREAT books that he would NEVER have selected. Neither would I have actually.
Anyway, now the problem is getting him to STOP reading and so that he can do his other school work. lol!