Format Memory Card
G button U B setup menu
Format memory cards. Memory cards that have been formatted in a computer or another camera should be reformatted using this option before use. To begin formatting, choose a memory card slot and select [Yes]. Note that formatting permanently deletes all pictures and other data on the card. Before formatting, be sure to make backup copies as required.
Do not turn the camera off or remove memory cards until the message [Formatting memory card.] clears from the display.