1. Connect to AC adaptor and charge for at least 1 hour.
2. If still not on, reset phone (no data loss): Press both home and power buttons for up to 40 seconds, releasing when the Apple logo appears.
3. If still no signs of life, your phone is passed on, demised, bereft of life, is no more, taking the dirt nap, pushing up daisies, of interest only to historians.