A PC, a compatible USB cable, and software like Nokia Care Suite or the Nokia BEST (BB5 Easy Service Tool) .
If standard resets fail, the phone's firmware may need to be "flashed" or reinstalled. Nokia C3-00 Security Code Not Working
If you are completely locked out of the device, you can attempt a "three-finger" hard reset to bypass the code and restore factory settings. Turn off the phone completely. Press and hold the following three keys simultaneously: (3) Three key Call/Send button (Green key). A PC, a compatible USB cable, and software
When the security code for a Nokia C3-00 is not working, it is usually because the default code has been changed and forgotten, or the phone has entered a temporary lockout state after too many incorrect attempts . Turn off the phone completely
While holding these, press the until the phone vibrates or the Nokia logo appears.