Iphone 4 won't turn on - 2

I have an Iphone 4, and just recently it stopped turning on. I turned it off, and went to turn it back on but it'snot working. When I try to turn it on, it acts normally as if turning it on any other day. But it only stays on the apple logo and has been for a while. It's not dead because when i turned it off, i still has at least 70% battery left. I've tried charging it still though, and that isn't working. I've also tried holding the home button and the lock button at the same time, and the phone will turn off, and start over again with the process of staying on the apple logo. I plugged it into the computer, but it didn't work either. What should i do?

This tutorial will fix it your problem:

If you're jailbroken, you'll need to rejailbreak afterwards. If you're on iOS 6.1.2 or lower:

If you're on 6.1.3 and you have an iPhone 4, 3GS, or iPod Touch 4:

Hope this helps!