What do you do when you just dont care anymore?

i've become cynical and depressed to the point where nothing matters anymore, not my life or anyone around me. i dont care about my money, or my car, or my job or school, im thinking about dropping out of college simply because i just dont give a **** anymore. its sad i know, and a waste,but i cant help feeling this way, im too depressed, my depression mildly started years ago and because it went untreated, over the years i became a manic depressive, dark, cold and dreamless. i just dont know what to do anymore, suicide seems like the only way out of this grave.