How to Upgrade Your iPod Touch to iOS 4.2.1
The iOS 4.2.1 has officially released by Apple and is now available to download or upgrade.It brings features like folders in iPad, Airplay, Airprint etc. If you want to upgrade iPod Touch to iOS 4.2.1,Then
You could upgrade your iPod Touch to iOS 4.2.1 in two ways : Automatically and Manually.
Updating to iOS 4.2.1 Automatically Via iTunes
1. Download iTunes 10.1 from here.
2. Connect your iPod Touch to the computer.
3. iTunes shows an iOS 4.2.1 update message.
4. Click the “ Download and Update ” button to upgrade iPod Touch to iOS 4.2.1.
Upgrading to iOS 4.2.1 Manually Via iTunes
1. Download iOS 4.2.1 IPSW for iPod Touch.
2. Download iTunes 10.1 from the above link.
3. Connect your iPod Touch to the computer.
4. Choose your device from the left sidebar.
5. Press the Shift key(in Windows) or the option key(in Mac OS X), click on the Restore button.
6. Now browse to the iOS 4.2.1 IPSW file and select it.