My Iphone Had A Blank Screen And Is Dead, How Do I Fix It?

Not sure what could be wrong with it, have you banged it or got it wet or very cold ?

I would try plugging it directly into a wall socket if you can somewhere warm and leave it for a while.. Maybe it will come back to life sometimes when they get a really low battery you need to charge it for a while before it will turn on.

Similar thing happened to my old one just inexplicably died one day, if you ring O2 they will give you a number for apple to dispatch you a replacement and take yours away.

Call 611, they will talk you though an update, if you do not know how, make sure you get a case #.  If it continues they will send you another.   What it is is that is will not come out of sleep mode.  It was happening to mine

I'm not sure if this would help, but with mine, when it does that I always charge it again and it works.

After you know for sure it's not dead(after plugging it up for awhile) press the top right hand button at the same time as you press the muddle round button on you I phone at the same time. Child it down for a min and it should cut back on