iPhone 4 works/receives calls, screen stays black? No lock button!

Hi there.

Today I picked up my phone to use it and it seems to have froze/crashed on me.

I was accessing the text Messages app and while using it, and the phone froze on me. This has happened briefly in the past in other apps, but for only a split second. This time the phone became unresponsive and the screen was frozen with the messages app up and showing.

I triple clicked home and the accessibility options came up. These options were responding. I was able to go through the different options. I chose 'lock screen' in hopes I could hit the Home button and the screen would show again. No luck, and the screen stays black.

Now the screen is unresponsive. I can receive calls but the screen remains black while ringing. I can plug it into the computer but only Windows recognizes it. iTunes will not. Screen still stays black.

Everything I read mentions someone dropping the phone and something coming lose. Im not sure that would have happened, since it froze right in my hand. I would have held the Home button and Lock button, but my lock button has not worked for sometime now.

Im going to attempt to remove the back and see if i can re-secure any connections, but Im doubtful thats the problem. In the meantime, any help or suggestions are greatly appreciated!

Thanks!

Phillip