Q: I upgraded to iOS 4 and now my iPhone 3G is slower than ever. How can I go back to the old settings?
Before you attempt to downgrade the operating system of your phone, make sure that you back up all of your contacts and personal information on iTunes and your computer. In the processing of downgrading, everything will be wiped from your phone.
Once you've backed everything up, find a copy of iPhone OS 3.1.3 (iPhone1,2_3.1.3_7E18_Restore.ipsw). You can find this online or a on your computer. If you're using a Mac, it'll most likely be located in the iPhone Software Updated folder (Macintosh HD > Users > Yourname > Library > iTunes > iPhone Software Updates). If you're using a PC, this file will be in the iPhone Software Updated folder at C:\Documents and Settings\Yourname\Application Data\Apple Computer\iTunes.
Put your phone into recovery mode by connecting it via USB to your computer and switching it off. Once the phone has shut down, press and hold the power button and the Home button. After ten seconds, let go of the power button, but keep pressing the Home button until iTunes lets you know that your phone has entered recovery mode.
Once in recovery mode, you need to find the Restore button in iTunes. Right click or Shift-click on the button until you see a set of files to choose from. Select the same .ipsw you looked for earlier and click Choose. It'll take about ten minutes to restore, but this process should return your iPhone 3G to the factory settings with iOS 3.1.3. If iTunes tells you, after the process is completed, that your phone couldn't be restored, download RecBoot and run that application to exit recovery mode safely.
Tools mentioned in this entry:
More questions? View the complete Toolkit archive.