Damn it, that's tough!
Ok, dedicate some time to searching for them, look everywhere, think about where you last had them etc, unless you took them on a journey or something they should be in your house.
Secondly, working on those notes will have already helped you out, because you've been over the whole specification, and should remember some of it. Start writing them out again as revision, review everything, and forget about the fact you haven't got notes, especially when in other exams. Focus on the exam in front of you!