In order to hard reset a Siemens C45, you should perform the following steps.
Remember! Hard reset will delete all the data on your device; pictures, contacts, messages, apps and more.
Siemens C45 device will be brought back to the default configuration of a brand new device.
1. Power up the device.
2. Type in this code, *#9999#.
3. Voila, done, phone will now restart.