if it's broken, turn your DS and press the button as fast and hard as possible, than blow into it as hard as possible, than press it repeatedly again. you might need to do it again, but it should work.
Being unable to use the R button might compliate things slightly. But it's still very possible. Like you will need to use combinations for some projects.
I need to ask stuff on PM later by the way. But tell me if you can't.