IPhone 4 screen went black - lock button not working!

So today my iPhone 4 screen just went black. If I hold down the home button the voice control comes on, but the screen is totally black. Probably a month ago my lock button became unresponsive. I can't turn off my phone, lock it, or do the reset thing by holding down the lock & home button. I don't know what to do. As we speak i am resetting it on my computer, but i don't think that would work. Also, a couple months ago I got my iPhone conversation changed to a blue iphone rather than white. I don't know if something was disturbed while it was being changed and that's why its not working! I don't have any insurance on it or anything, so taking it to AT&T or Apple would probably be a waste of time. If I can't fix it myself I'll probably buy a new one, though I don't want to. Thanks!

Added (1). Sorry, it put this question in the wrong section. :/

Hold the home button and the on off button at the same time ten seconds, and it should reset other wise plug into itunes and see what happens, otherwise wait till it goes flat and then plug into itunes, it may be a big issue, if it comes on look in diagnostics (settings) and if it is a plist with a error contact apple, get applecare, and swap it out (could be a ram chip dud)