You probably need to reformat your SD, to make sure pull the battery and the SD and then put them back and power back up, if it still doesn't recognize it then you should mount the card to your computer via card reader and save what files you can
Erase the card and put it back in your phone, if it recognizes it then go to settings/sdcard and choose unmount and then select format (let it format)....then remount
If all goes well you shoult be able to mount to your computer via USB and drag your salvaged files back to your SD-keep in mind some files that you saved you will not want to put back on your SD card, these are the files that Android creates on the SD card upon start up and during format...you will see the files already on the card so don't overwrite the new ones with the old ones
If none of this works your SD card is under warranty from Verizon