In order to hard reset a Nokia Asha 303, you should perform the following steps.
Remember! Hard reset will delete all the data on your device; pictures, contacts, messages, apps and more.
Nokia Asha 303 device will be brought back to the default configuration of a brand new device.
1. Power up the device.
2. Open dialer and type in this key combo: * + 3.
3. Release the buttons when Nokia logo appears on-screen. Press Call button to confirm the process.
4. Phone will now reset and restart, completing the hard reset process. Yaay.