iPhone won't charge?

I had my iPhone on the USB charging from my computer for ~4 hours..yet it still shows the battery being in the "red zone". I got one call, and 2 texts. I don't want to restore...that is not an option, I'm trying to charge from a diferent USB cable into the wall adapter, but its not seeming to work..on the top right, I have the charge logo, but the center battery isn't charging.