To reset, hold down the sleep/wake button and home button at the same time
I can not reset YOUR iPhone 5, only YOU can do that.
plug your iphone into your computer and go into itunes click on your phone under devices go to summary and press check for update or update iphone.
No.
Update the software in iTunes and it will do it for you.
yes. the current update is 3.1.3 and to update to it you have to restore you iphone, update it then re-jailbreak it. but at this moment in time this is not an jailbreak for firmware 3.1.3.
What you do is you go and plug up ur iPhone to the iTunes and click on the update button
The update 6.1.6 helps to maintain the working efficiency for the iphone 3gs.
To reset an iPhone model A1387 (iPhone 4S), go to "Settings," then tap "General." Scroll down and select "Reset," then choose "Erase All Content and Settings." Confirm your choice, and the device will begin the reset process. Make sure to back up any important data before proceeding, as this will erase everything on the phone.
I don't believe the iPhone 3G can update past 4.2.1, but any newer iPhone can update the same way you normally update an iPhone through your iTunes authorized computer.
No, you do not need an iTunes account to reset an iPhone. You can reset an iPhone directly through its settings by going to "Settings" > "General" > "Transfer or Reset iPhone" > "Erase All Content and Settings." However, if you want to reset your iPhone using iTunes or Finder, you will need an Apple ID to back up or restore data.
You can eithr do it on the phone through settings or you can hook it up to itunes and do the update that way. Either way takes about an hour. Good luck
Considering updating your iPhone forces you to update to the latest software available for the device, updating an iPhone 3GS now will update it to iOS 6.