Apple released iOS 4.3 for their popular gadgets like iPhone 4 , iPhone 3GS, iPod Touch, Apple TV and iPad. The latest version iOS is not supported in iPhone 3G and iPod Touch 2G.
Download iOS 4.3 (Note: You can download it only if you have a Apple developers account)
Steps to downgrade iOS 4.3 to iOS 4.2.1 or 4.1
- Download the old iOS versions to which you want to downgrade.
- Put you Apple device in DFU mode
How to put an iOS device in DFU mode ?
- Connect the device with your computer and turn the device off.
- Press the power and home buttons together for 10 seconds.
- Release the power button and hold the home button until the computer recognized your device.
- Go to quoted location below and find the file named ‘hosts’ (Note: If you are using MAC OS X you can find the directory ‘etc’ easily by ‘Finder’ feature.
C:\Windows\System32\drivers\etc\
- Open the ‘hosts’ file with a notepad or any other text editor software. Add the below quotes and save the file.
74.208.105.171 gs.apple.com
- Start iTunes application and select your iOS device from the sidebar.
For MAC users: Hold the left ‘Alt’ key
For Windows users: Hold the left ‘Shift’ key
You can see a window with two buttons, Check for update and Restore. Click on Restore button.
- Go to the location where you saved the old iOS version file. Select the version to which you want to downgrade and click on ‘open’ button. It will start the restore operation. The device will restart automatically after the process completion.
How to get rid of 1013 error during the restore operation ?
Sometimes you will experience an error code 1013 during the restore process. Ignore it, there is no need to worry. Use this application(Download TinyUmbrella: For Windows, For MAC) if it cause your device stuck in the recovery mode.



Thanks for the tip.Will follow your steps
Nice tutorial… I am using iOS 4.2 on my iPad….