What do you mean by won't power on? When you plug it in, do you see a white light in the LED light at the top? When you power on, what do you see on the screen?
If the battery is very low, so low that the phone will not start up, the worst thing that you can do is plug it into a computer. A computer's USB port puts out too little current to charge the battery in that state, and it ay end up discharging the battery more.
i Mean it wont power on, the screen is blank it doesnt come on, no power, dead. i've tried wall charger and car charger. The LED light isnt at the top its next to the charger port. The screen shows nothing because it DOESNT power on at all.