iphone 4 is not turning on

Hi,

I have an iphone 4 its battery is empty when i used to switch it on from

the power button it gave the battery with the red line.

But after one hour when i pressed the power button it didnt switch on and

didnt give me anything and screen is black.

I plugged it to the wall socket and it didnt turn on and i have waited 15

minutes and didnt turn on after that i wanted to check if the usb cable is

working i connected it to the computer it gave a sound as if a device is

connected it says device not recognized and i checked if the adapter is

working and all is fine.

I then left the mobile for 30 mins to charge from the wall socket but it

still didnt turn on what may the be please tell me fast.

I want to tell you also that i have tried holding the power button and the

home button and didn't get any result.

Nothing appears on the screen even the battery logo or the apple logo.and

its not turning on.