Apple iphone 4 won't turn on?

It has just been on the black background with the apple logo? Its fully charged. I can't plug it into itunes because its got a password on so it says it can't open up my phone in itunes until the phone is unlocked, but i can't unlock it because i can't properly get onto my phone! Please can you help! Also don't say to send it off to apple because i can't do that, surely there's other ways? Thank you, answer that makes my phone work properly again will get the best answer!

Power battery is down.

I've had this problem before, the only way I found to fix it is to do a full reset by plugging it into computer and resetting but you said you can't do that… The only thing I can suggest is a hard reset- hold power and home button at the same time until the screen flashes and shuts off, then give it about 5 minutes to start up. If its still on the apple logo then i don't know what to tell you

You're stuck in a recovery loop. Use the program tiny umbrella which is for windows mac and Linux. Use this to kick it out of recovery mode.