I had the same problem with my phone. First, make sure it's plugged in, if not, then it's obviously not going to work. But if it is plugged in, unplug it and wait a few minutes, then plug it back in. I found that my phone was actually unplugged. I plugged it back in and it is working now. So the first thing you should do before unplugging the phone, is make sure it is actually plugged in already.