How do I restore a jailbroken iPhone 3G? How do I restore to the normal non jailbroken state my jailbroken iphone 3G? Is there any permanent change when you jailbreak it?
All you need to do is plug your iPhone into iTunes, click on it under Devices:



And click "Restore":



iTunes will make sure that you do actually want to restore:



Jailbreaking does not make any permanent changes; a restore will put your iPhone back exactly the way it was before you jailbroke it.