Troubleshooting iPhone and iOS4

• If you are experiencing any issues with your iPhone the first thing to try is to restart or reset your iPhone by holding down the sleep and home buttons until the Apple logo appears.
• If you are experiencing network issues then open the Settings app, then go to General -> Reset, and choose “Reset Network Settings” this will reset all your network settings to the factory defaults. If you had any Wi-Fi network passwords saved you will lose these and have to re-enter them the next time you connect to a one of the previously saved networks. If you are not experiencing network issues go to the next tip below.
• If you are still having problems then open the Settings App , then to go General -> Reset, and choose “Reset All Settings” (note: this will not erase your apps, media, or other data — that’ what the “Erase All Content and Settings just below this option will do). “Reset All Settings” just restores the factory default Settings preferences that you might have customized (i.e. your ringtone, etc.).
• Finally if none of the first three troubleshooting tips work you can restore your iPhone by plugging it into a computer running iTunes. It is recommended that before proceeding that you allow your iPhone to sync and perform a backup in iTunes before continuing. Once you’ve confirmed that you have a good back up then in iTunes, locate and click the Restore button under the Summary tab for your iPhone. Restoring the phone will erase contacts, calendars, photos, and other data on the phone, but will restore automatically backed-up information including text messages, notes, call history, contact favorites, sound settings, widget settings, etc.

{source: cultofmac}
{photo: theglobeandmail}