01-05-2013 05:07 PM
01-05-2013 07:00 PM - edited 01-05-2013 09:42 PM
Couple of things could be going here. Check this link to enable media card support.
You could also remove the battery, reseed the sd card and power the phone back on.
You can also go here to attempt to format the card from your phone:
The card could have a physical problem if these steps don't work. Did you have files on the card before and they disappeared? Are you able to connect the phone with the card inserted to the computer and access it with a drive letter on the computer?