My iphone 3g has a black screen?

ok so first my earpiece was messed up so i opened up my iphone then i disconnected the first three cables and fixed the earpice when i was puting the cables back together i put them on right and then the #1 cable went in and snapped back out so iput it back and the screen just went black and ive tried reconnectiong all cables but nothing works i restored i even resetted and nothing works everything works vibrate yu can even hear the messages coming in but no view of the screen btw i just replaced the lcd so i dont think it coul be the probem but help pleaseeee i fell like my iphone is dead......