Curious how to restore your iPhone, iPad, or iPod touch when it's acting funny and nothing else will work? Need to install a beta or custom firmware? Whether you're experiencing freezes, crashes, or your iPhone or iPad is just doing other crazy things - a restore will fix most of your woes. Restores are also something developers need to know about to test beta firmware, and jailbreakers should become very familiar with, as sometimes it can make your phone a little less stable than it is stock.
To restore, whether on a Mac or PC:
When the restore has finished you'll be asked to either set up as a new iPhone or restore from a backup. If you choose to restore from a backup and your device still acts funny afterwards (i.e. the problem returned with the backup), I'd recommend doing the restore again and this time setting up as a new device. Then re-sync your content.
To install different or custom firmware (say you need to test iOS 4.2 GM or say you're on 4.0.2 and you don't want 4.1 for some reason), hold down Option (Mac) or CTRL (Windows) while you click restore, then navigate to your then navigate to the firmware you want.
This is a pretty basic function of iTunes but one anyone that owns an iOS device should learn how to do. Always make frequent backups and sync your phone regularly to ensure you won't lose your content if something should go wrong with your device.
Let us know how it works for you and if you have any questions, ask in the comments!
Tips of the day will range from beginner-level 101 to advanced-level ninjary. If you already know this tip, keep the link handy as a quick way to help a friend. If you have a tip of your own you'd like to suggest, add them to the comments or send them in to firstname.lastname@example.org. (If it's especially awesome and previously unknown to us, we'll even give ya a reward...)