IPhone 4 screen went black? Lock button also hasn't been working?

Last night I was just sending a video to my friend and my phone went black. It is completely unresponsive to anything! I plugged it into the charger and nothing happened. I plugged it into my computer and nothing happened. My computer didn't even showed it connected. So I plugged it into my regular wall charger and went to bed hoping it would be back to normal in the morning. But it still isn't and it has been 7 hours! I am freaking out. What should I do? And by the way, the video I was sending is a very personal one so I don't want to go to Verison and ask them to fix my phone and then that coming up on the screen… Please help me!

Pics or it didn't happen!

Try holding the home and the lock button for 20 seconds if you see the apple you can release the buttons but if nothing shows try going to the store where yo bought it.

Probably your unit is dead. Even when you try to do anything. It won't do any help at all. Go to a nearest repair shop and have it check.