I charged my Fire 7 but doesn't work.

I used to use a Amazon Fire 7 Tablet and found it a couple of times but whenever I charge it like yesterday, I charged it for a whole day but still nothing happens even when I hold the power button or both of the Volume buttons. i also wanna try to get my stuff back also. Do you think you guys can help me in any way? (I haven't and don't know how to open the tablet)