You have a bricked Windows Phone 8. Your Windows Phone is not responsive. Your windows phone might be bricked when you are tying to reset using hardware keys or You might be installing ROMs or trying few apps on it.
If you can’t power on your Windows Phone like Lumia 920, 820, 810, 822 or HTC 8X etc, There is a chance It might be bricked. There were few problems with wireless charging also. Sometimes, You see your phone stuck at cog wheels or gears or not getting past Nokia or Windows Phone screen. Your Windows Phone screen is frozen and not responding.
How to fix bricked or unresponsive screen Windows Phone 8
You can easily soft reset your Windows Phone If its not responding. This is same as battery reset. Press and hold Power & Volume Down buttons for about 10 seconds. Your Phone should boot normally. Thats it. This works in most cases.
If your phone does not start or stuck again, You may want to look at other options like Flashing. But do it If you know what you are doing. You may just want to take your Phone to store and exchange your Windows Phone.
Make sure your Windows Phone has enough battery to boot. You can connect Power cable to Windows Phone and see If it charges or displays low battery.
Also read, how to backup contacts on Windows Phone 8