Ummm.. i cant sing anymore!!?

Your voice has broken. But of course I don't mean it's been destroyed... but rather it has become deeper. Women's voices deepen slightly quite naturally over a long period of time but mens voices on the other hand, at approximately your age, deepen a great deal more and all at once! This is natural too. Don't force yourself to sing in a particular way, because forced/painful singing can actually cause permanent damage to your vocal cords. Seek professional advice.