IPhone won't turn on but vibrates!

Hello everyone, today I've got a big problem; my iPhone isn't working anymore, the screen is black, it hasn't fallen, it was just in my pocket. I take it out and then nothing, black screen. I'm thinking that it's "fried" and won't work anymore, but then someone calls me and it starts vibrating (screen still black). I go home, take my landline and call, and it still vibrates. I've read some things online that say to press the home button and the power button for 10 seconds + 10 seconds on the home button, etc. Nothing works, and now after pressing all these buttons, it doesn't vibrate anymore. When I connect it to iTunes, it recognizes it, and I've tried to restore it, but it gives me an "error." I don't know what to do anymore, can you help me? Thanks.