My iphon will not turn on - Apple iPhone Smartphone

First check to make sure your charger is working, plug it up to the computer and see if the battery charging display comes up.

Second I would check to make sure the battery is actually charging.

Third try a cold boot, hold the power and home keys down while it boots it could just simply be locked up.

try to do one thing that is press the start and home button together and then see

Connect it to iTunes, you might need to activate it, or restore it.
that's all that means. There's no verifiable OS active on the phone

If something isn't working right, restarting, force quitting an application, or resetting
iPhone will likely solve the problem.
Restart iPhone: Press and hold the Sleep/Wake button until the red slider appears.
Slide your finger across the slider to turn off iPhone. To turn iPhone back on, press and
hold the Sleep/Wake until the Apple logo appears.
If you can't turn off iPhone or if the problem continues, you may need to reset. A reset
should be done only if turning iPhone off and on doesn't resolve the problem.
Force quit an application: Press and hold the Sleep/Wake button on top of iPhone
for a few seconds until a red slider appears, and then press and hold the Home button
until the application quits.
Reset iPhone: Press and hold the Sleep/Wake button and the Home button at the
same time for at least ten seconds, until the Apple logo appears.

I had a similar problem after I updated my iPhone 3g's software to 4.0.1. I read that if you turn off your iPhone, then with your car/stereo turned off, plug in your iPhone. Now turn on the car/stereo which will turn on your iPhone automatically and "re-initialize" the relationship with the iPhone. This worked for me. Hope this helps. If not, check the Apple forums.

Find your solution from the list,
Apple Iphone Smartphone
Codes:

• Unlock Code,
• Password,
• Puk Code,
• Lock Code,
• Other Codes.

Software & Hardware Problems

• Software Problems (Hang, Youtube etc.)
• Hardware Problems (Display, Charging etc.)

Find Your Solutions for other Apple Products:
Apple Iphone 3G
Apple iPod Touch Digital Media Player

You can restore your iPhone if you don't know the passcode this can be done by :

1. While your iPhone is turned on connect it to iTunes via USB cable
2. Once iTunes has recognised the iPhone turn your iPhone off and DO NOT disconnect it.
3. Turn your iPhone on while pressing the home key
4. When the Apple Logo appears let go of the power key but keep pressing the home key until the screen goes blank
5. This will put your iPhone in recovery mode and your PC will recognise it as "iPhone DFU mode"
6. Once this happens go back to iTunes and you will have the option of restoring your iPhone.
   

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