For more information on your device, select it on the Support main page.
Check that your device is not connected to PC over USB connection using the Mass storage mode. If connected in Mass storage mode, the mass memory access is reserved for transferring files to / from PC and the device applications cannot at the same time access the mass memory or memory card. The File Manager application will show in this situation the message "memory in use" or "memory card in use" when trying to view the mass memory contents.
To access the mass memory or memory card again, unplug the USB connection or use the PC Suite or Nokia Suite mode instead of Mass storage mode when connecting the device to a PC.