My iphone ran out of battery and now it won't turn on?

My Iphone ran out of battery meanwhile i was using it so then i go ahead and charge it i come back 10-20mins. And it wouldnt turn on for some reason so then i tried another charger for the somae amount of time but still nothing it wouldnt turn on so i tried a third charger and i charged it for about a hour and still nothing no picture or anything like its all lifeless i tried holding the power button, but still nothing, i already tried resetting it and all and i also already tried connecting to iTunes in recovering mode can someone please help me i have some really important stuff in it so can someone fix it without resseting all the settings
iPhone 4, iOS 5.1.1

Have you tried holding the Power button and the Home button together?

An iPhone must have a minimum battery charge to turn on.

As long as that charge icon is still appearing when you plug it in, nothing is wrong with it.

Just let it actually charge for an hour or two

If its turned off/dead you have to hold the power button (on the top) for a few seconds until the apple logo appears then let go. Not the home button. For some reason the home button won't turn it on, only the power button (on the top)

The same things just happened to mine!