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Restarting and Resetting iPhone

If something isn’t working right, try restarting iPhone, force quitting an application,
or resetting iPhone.

Restart iPhone: Press and hold the On/Off 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 On/Off Sleep/Wake button until the Apple logo appears.

If you can’t turn off iPhone or if the problem continues, you may need to reset iPhone.
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 On/Off Sleep/Wake button on top of
iPhone for a few seconds until a red slider appears, then press and hold the Home
button until the application quits. On iPhone 3GS or later, you can also remove an
application from the recents list to force it to quit.

Reset iPhone IOS4: Press and hold the On/Off Sleep/Wake button and the Home button at
the same time for at least ten seconds, until the Apple logo appears.

Apple iPhone ios4 hard reset

Apple  iPhone 3GS hard reset Apple iPhone 3GS soft reset

New IOS 7 reset from menu

Apple iPhone ios 7 reset

General advice: Before you buy a new cell phone or new tablet, please try the following procedure to repair your device in a software way. First charge your battery, backup your important data if possible and in most cases take out SIM and SD card before doing factory reset. It is impossible to recover your data after doing a hard reset, so online backup is always important. For all of your data, a backup should be done on an external device, hard drive, raid system or media. With or without insurance, if your cell phone lost, damaged or stolen at least your invaluable data is backed up in a safe place. If you are about to sell your phone and you want to wipe your personal data, or if your phone affected with virus you have to do a hard reset. In some cases, you can delete the forgotten password or lock pattern from your device as well. All information is for devices with stock based ROMs. If you are using rooted device, always back up your EFS folder first, containing your IMEI info, etc.! Please also note, that a hard reset operation will not unlock your mobile phone's SIM lock or network lock, but it will remove the unlock pattern, remove the user password or PIN password (NOT the SIM card's 4 digit PIN code). Also note that the firmware version will not be affected in any way, it will not be downgraded, it will remain the same you are using and if you have rooted your device, root privileges remain also unaffected.