- 1). Press the "Menu" key, and select "Open Tray" to view a list of applications installed on your BlackBerry.
- 2). Select the "Options" entry in the application tray. The "Options" entry is represented by a wrench icon.
- 3). Scroll down in the "Options" menu, click "Device," and then click "Storage" to edit your BlackBerry's memory settings.
- 4). Press the "Menu" key and select "Format" from the menu. A dialog box will appear asking you which storage location you want to format.
- 5). Select "Media Card," and then select "Yes" to format the memory card in your BlackBerry.
Source...