*In the video we use an iPhone 4 to demonstrate the procedure, the procedure is identical to the way to do it for any iPhone.
So maybe you need to turn your iPhone 3G in for warranty or maybe you just are done with changing your icons, messing with Siri, and just want to go back to the way things were before; nice and safe. Regardless of why, here’s the how. In this tutorial, we’ll show you how to take your jailbroken iPhone 3G and unjailbreak it so it’s all back to stock. We can even show you how to do that without losing your data.
I. Before You Begin
1. Make sure you have the latest version of iTunes installed.
II. Create a Backup
1. Plug the device in to your computer via USB cable.
2. If iTunes doesn’t automatically open, open it.
3. Wait for the iPhone to sync, and then select File at the top of iTunes then Devices then Backup and wait for it to backup the device.
III. Unjailbreak the iPhone
1. In iTunes, select View and then Show Sidebar.
2. In the Sidebar on the left, select the iPhone.
3. In the main window, select Restore iPhone at the top.
4. Wait for it to Restore your iPhone. Once done, you’re all back to an unjailbroken state.