iPhone's screen went black and buttons stopped working

None of my iphone buttons work. Today my phone died, so I plugged it in. A min later I heard it come alive. The screen is completely black now tho. The only working button on my phone is the silencer button, and i can feel/hear it vibrate between silent on/off. I can hear it charging when i connect the charge cable. My computer is not detecting any connected device.

What do i do...

[Re-Titled by Moderator]