why won't my iPhone 5s turn on?

why won't my iPhone 5s turn on? I've done all the tricks with holding down the home and power button and letting it charge but nothing happens except a white screen with the black apple appearing then disappearing. I also held down the home and power button for 30 seconds and the screen changed from black to white at least two times then it told me to plug my phone into iTunes, please tell me that I didn't just reset my phone. I'm also behind on at least one update so I don't know if that has any affect on it.. Any help is appreciated cause I'm kinda panicking about losing all my phones data and pictures and text messages...