I can't close my Iphone 4

Hello

I can't close my I phone 4. After a conversation on messenger the image blocks and the buttons are nonresponsive. After 5 min the image turns in green lines, the buttons still nonresponsive ( I pressed for 10 sec and more both buttons) after this is turning black and a battery descharged appear when the sleep button is pressed. I was waiting the battery to descharge but is the second day and still is not empty. Through I tunes I can't detect my device. Please I need help.