Resetting iPhone:
If you have your stuff backed up via iTunes, then you can follow following steps to get it back;

1) Plug the phone in to your computer.
2) Turn it off while its plugged in.
3) Hold the POWER button for 10 seconds.
4) Now hold the Home button WITH the Power button for another 5 seconds or until USB/iTunes logs come up.
5) let go of the buttons and restore firmware.

SETTINGS–> GENERAL–> RESET and then Erase all comtent and settings

Reset the iPhone by holding the sleep/wake button at the top right of the device and the home button at the bottom center of the face at the same time. Hold them both until you see the screen go black and the white Apple logo appear. When this happens, you can let go – the iPhone is rebooting.