Buy a new one. They break lots. (I'm on my 4th)
Amazons return policy is stellar. I've paid for one, 3 have broken yet I've never spent less than 3 days without a fully functioning Kindle.
Two friends are still on their first, so they are sturdy to a point. But I treat mine like a book. Tossed into bags, no case, left here there and everywhere. If it's going to replace a book, it has to be able to man up like a book. I stop short of using it as a coaster though.
Amazing devices though. Amazing. Haven't got a bad thing to say about them other than;
Don't let a child turn it on and off repeatedly as a game.
Don't leave one on top of the microwave
(The other one died of natural causes)