In order to hard reset a Samsung E800, you should perform the following steps.
Remember! Hard reset will delete all the data on your device; pictures, contacts, messages, apps and more.
Samsung E800 device will be brought back to the default configuration of a brand new device.
1. Power up the phone with the Power button.
2. Type in this code, *2767*3855#, and confirm it.
3. Your phone should now reset and restart. Done.