why has my iphone turned off and now wont turn on

Hello Hopp3r,

Thanks for using Apple Support Communities.

As I understand your post, your iPhone 6 is unresponsive and only displaying a black screen. In order to troubleshoot this issue, please follow the directions in the article linked to below.

If your iPhone, iPad, or iPod touch doesn't respond or doesn't turn on - Apple Support

Have a good one,

Alex H.

That exact thing happened to me. It turned off unexpectedly and wont turn back on.The battery had not died. I tried holding the sleep/wake button and the home button for the 10 seconds and it responded and came back on. But why did that happen though?

iOS crashed. It happens to all operating systems. You're probably familiar with the Windows Blue Screen of Death. Unix/Linux/OS X Kernel Panics are the same thing. Even IBM mainframes crash (SYSABEND).