Have a 2003 chevy trailblazer: battery went dead overnight, fixed battery now engine wont turn over

Common problems when battery died over night usually cause by someone left a light on, it can be the door is not being close completely to over head/map light and not knowing it. have the alternator check, any auto parts store can test it for you. to see if it working properly. next is to check the battery cells to see if its good and maintain its charge, auto parts store can also test it for you. a bad cell will also cause the battery not to hold or retained its charges. get a jump from a friend and see if your car will start. if its does than it will be your battery.