If you don’t want to keep the changes made on your devices during your last sync, you can reset the information on your devices to match the information on your computer. You may also want to reset information on your devices if you’ve had problems syncing and you want to “start over.”
Important:Resetting your devices erases the calendar and contact information on your devices and replaces it with the information on your computer. Any contact or calendar information on your devices that is not also stored on your computer is erased. For example, you may lose any speed dial, voice dial, or custom ring information on your mobile phone.
Once the reset has begun, you cannot cancel it. Clicking the Cancel Sync button in iSync (or choosing Cancel Sync from the sync status menu) while the reset is in progress only postpones the reset until the next time you sync.
To replace the information on a single device with the information on your computer, select the device’s icon in the iSync window, and then choose Devices > Reset “device name,” where “device name” is the name of the selected device.
To replace the information on all your devices with the information on your computer, choose Devices > Reset All Devices.