Sometimes You have to wipe your iPhone’s memory clean to fix the problem which means if you have syncing issues, application problems or a lot of freezing on your iPhone, doing a full restore could solve problems. Of course, you can back up the applications and any important information you have stored before cleaning your iPhone’s memory.
1. Open iTunes on your computer and connect your iPhone to your computer with the Apple USB data cable.
2. You can find “Devices” on the left side of the iTunes window and then click the iPhone icon under it. This will open options for your device in the main window.
3. Click the “Summary” tab > Click the “Restore” button
4. Select “Back Up” from the pop-up window that appears. After doing that you can put all the important data back to your iPhone after it is restored. You can select “Don’t Back Up” if you do not want to use this option or you just synced your iPhone to iTunes. If you want to erase everything from the phone after the restore, you must delete the items in iTunes so it does not re-sync with the phone.
5. Click “Restore” when the window pops up. And then click “OK” when it finished.
6. You will get the “Connect to iTunes” message on your phone. Do not disconnect the phone from the computer, and wait until the message disappears or “iPhone is activated” appears on the screen.
7. Select “Set up as new iPhone,” or choose a restore point from the screen that appears on iTunes and click “Continue” to complete the restoration.