Last Updated: Oct 22, 2014
Be sure all of your contacts are visible.
If you saved your contacts to the phone storage on either your HTC One® or a previous device, you can recover your contacts.
Google Sync is a free service that synchronizes your HTC One with your Google™ (Gmail™) account. If you've saved your contacts to your Google account, you can restore them to your device.
Some Bluetooth-enabled devices have Bluetooth file transfer capabilities. If you stored your contacts on another Bluetooth-enabled device, you can recover your contacts.
Note: Sprint recommends you save your contacts to your Google account.