If your iPhone 5 isn’t turning on the first two things to do is to make sure it’s charged and then try to turn it on. Sometimes even though you plug it in to charge, it won’t if there is debris that is keeping the cable from completely connecting or if you are plugging it into your keyboard as the iPhone 5 needs more power than many keyboard outlets provide. Check your cable and connectors to make sure they are clean and then plug your iPhone 5 into a wall outlet. After your iPhone 5 has had time to charge, try to turn it on again by holding the Hold button down.

If your iPhone 5 still isn’t turning on after you know it’s charged and you have tried to turn it on, restart it by continuing to press the Hold button down until the red slider appears or it turns off by itself. Often times, restarting your iPhone 5 will get it to turn back on. If it won’t restart, press the Hold and Home buttons down at the same time until you see the Apple logo appear, this can take about half a minute or so and will force the phone to boot up.

If forcing your iPhone 5 to boot up doesn’t work, then you may need to restore it to factory settings. While this will erase all your saved data, you can reload that later from any backups you’ve done at iTunes or iCloud. To do this, plug the USB cable into your dock connector on your iPHone 5, but not into your computer yet. Press the iPhone’s Home button and plug the cable into your computer while continuing to hold the Home button down. This action will open iTunes and put the iPhone into recovery mode so you can restore it to its original settings.

If none of these actions are helping, it might be that your battery needs to be replaced or that your iPhone 5 is having some other problem. If you have had your iPhone for less than a year and it is still under warranty, or if you have AppleCare, then contact Apple to have your battery replaced for free. Otherwise, call Apple Support or take your iPhone 5 to your local Apple Store for repairs.

Source About iPod