In order to hard reset a Samsung T669 Gravity T, you should perform the following steps.
Remember! Hard reset will delete all the data on your device; pictures, contacts, messages, apps and more.
Samsung T669 Gravity T device will be brought back to the default configuration of a brand new device.
1. Press-hold the Power button until the phone turns on.
2. Select Menu > Settings > Backup & Reset > Factory data reset.
3. Continue to Reset device > Erase everything. Voila, the factory reset is over.