iphone 4 locked up.

Hi,

my iphone 4 just completely locked up when I was tryign to answer a call last night. Then screen went black and nothing since. How may I get my phone working. But before you can get your canned responses ready, I have a couple of parameters on answering question.

1) You can't use the response: "Push the top and front button" (When I do that for 8 to 10 seconds, all i get is the screen telling me my phone battery is about to die, but it never quite does, there is still a little juice, if only the battery lasted as long when the phone worked).

2) You can't use the response: "Plug into computer and reset with Itunes." My computer does not recognize the phone is connect via USB.

So what would be option #3?

Thanks for your time

C