When I was younger I read a book series, possibly only a trilogy, about a boy who was confined to a wheelchair. he was transported to another world somehow, I can't remember. he meets this girl and they have to save their land or something. does this ring a bell? He might also possibly be using braces instead of a wheelchair I'm not sure.
It was in English. I know that much. One of the covers had blue people coming out of a wave or the ocean. I think the main characters name started with a J. I most likely read this book from 2008 to 2010.
The main characters name might be Kip or Kit, those are both ringing a bell. And I know that in the beginning he talks about feeling invisible.