Drained/dead battery
Plug
your iPhone into your computer or wall adapter to charge. If it does
not charge when connected to either of these, you probably have a dead
battery. The battery will need to be replaced (
GSM (AT&T) or
CDMA (Verizon)).
Bad display
It
is possible that it appears nothing is happening because the display is
bad. If the iPhone sounds like it is working properly but nothing is
visible, it is possible the display is bad and must be replaced (
GSM (AT&T) or
CDMA (Verizon)). Unfortunately, the LCD and glass panel are fused together, and must be replaced as one unit.
Bad logic board
If nothing else works, your logic board is probably bad and needs to be replaced (
GSM (AT&T) or
CDMA (Verizon)).God bless you