Reset iPhone 3GS http://snapvoip.blogspot.com/
After our post "Reset Your iPhone To Factory Setting. (Low Level Format Your iPhone)" getting much attention, we have decided to add the complete iOS based iDevices to the list. So today I will start with resetting iPhone 3GS to Factory setting.
This time we are following a different but safer path. We will be using iTunes to reset the iPhone 3GS. Before going on this path, first make sure you have the latest version of iTunes installed and running on your computer, be it MAC, Windows or Linux (with wine and that is another article) before attempting to reset your iPhone 3GS to factory setting, once you are ready, Connect your iPhone 3GS to your computer.
Select your iPhone 3GS when it appears in iTunes under Devices.and you are done. Enjoy, sell or give away your renewed iPhone 3GS.
Select the Summary tab.
Select the Restore option.
Select the Back Up option if you have not backed up the device recently.
Select the Restore option when iTunes prompts you if you have the device backed up.
Once the restore process has completed, the iPhone 3GS restarts and displays the Apple logo while starting up and then iPhone displays the "Connect to iTunes" screen. Keep your device connected until the "Connect to iTunes" screen goes away or you see "iPhone is activated."
If iTunes does not have an Internet connection, you cannot complete this step, so make sure that you are connected to the Internet.Very important---If you want to preserve previous backups that iTunes has made, be sure to back up the appropriate directory before choosing to set up as new.
On a Mac: ~/Library/Application Support/MobileSync/Backup/
On Windows XP: \Documents and Settings\(username)\Application Data\Apple Computer\MobileSync\Backup\
On Windows Vista and Windows 7: \Users\(username)\AppData\Roaming\Apple Computer\MobileSync\Backup\
The final step is to setup your iPhone 3GS as New, so select "setup as new" from the following menu;