In order to hard reset a Karbonn K9 Jumbo, you should perform the following steps.
Remember! Hard reset will delete all the data on your device; pictures, contacts, messages, apps and more.
Karbonn K9 Jumbo device will be brought back to the default configuration of a brand new device.
1. Turn on the phone by holding down the Power button.
2. Now press the Call button (green handset one) and type in this code, *#8929#
3. Phone will now reset and restart.