iPhone 4 on 4.1 with blank screen (black, doesnt show anything) but if you click the home button or sleep to wake the phone, then slide the unlock thing to the right it will make an unlock sound. it also shows up as regular iphone that you can sync in itunes - but screen SHOWS NOTHING!

help?

Most likely a hardware error/fault. You can either buy a replacement digitizer & LCD assembly and replace yourself if you are good at taking things apart carefully and putting them back together, or you can bring it to an authorized repair shop. I'm assuming the Apple Store is out of the question?