Many people are concerned that once they jailbreak their phone they won't be able to get warranty service or fix a problem if something goes wrong. Fortunately, there is almost always a way to bring your phone back to a completely factory state -- and from there you can get help fixing your device.
Try each of these methods in succession. The first method is the easiest and least likely to work, the last method is a full-restore and is almost guaranteed to wipe your iPhone clean and leave it with factory settings.
Method 1: Basic iTunes Restore (No Data Loss)
- Connect your phone to your computer and open iTunes. Select your device in the left menu and click on the "Restore" button.
- iTunes will ask to backup your device -- select yes. It will only backup non-jailbroken applications and will restore all of your app store applications and preferences.
- The new firmware will be downloaded, extracted, and installed. Your device will restart when it is finished.
- After your iPhone activates you can restore from your backup (if you created one) and you will get all of your non-jailbreak applications back. Your phone will still be un-jailbroken if you do this.
- All set! Your phone should no be back to normal with little or no traces of jailbreaking activity
Method 2: Restore from iTunes as New Phone (Lose Data & Settings)
- Connect your phone as previously described and click restore. This time select "Restore iPhone as New"
- Your phone will be wiped clean and the factory firmware will be installed
- Once the process is finished, your phone will restart and will be activated. You'll now have an entirely jailbroken phone, but will need to reload all of your applications and music/photos.
Method 3: DFU Restore
- Connect your device to your computer and open iTunes
- Enter DFU Mode. Do this by pressing the power and home button until the red slider appears to shut down your phone. As soon as the slider appears, count to 5 seconds and then release the power button (but keep holding the home button). Wait another 5-10 seconds and iTunes should prompt that an iPhone has been connected in "restore mode".
- Find/download and install the firmware version that is appropriate for your phone, all of this is done through iTunes.
- Tada! Now your phone should be completely wiped clean of all data and traces of jailbreaking activity. You can now take the phone to get help with whatever problems you were having, or simply reload your applications and continue using as it was when you bought it.
Important Note: All of these methods have been tested and work very well for most people. They are not complicated and should not cause any problems -- however, remember that things do sometimes go wrong, and you are doing all of this at your own risk.