In order to hard reset a Nokia C1-02, you should perform the following steps.
Remember! Hard reset will delete all the data on your device; pictures, contacts, messages, apps and more.
Nokia C1-02 device will be brought back to the default configuration of a brand new device.
1. Power up the phone.
2. Open the dialer, enter this code into it - *#7370# - and confirm.
3. Device will reset and restart.