I had a problem with my external SD card and was curropted showing in app. manager.

What i did is removed the card and put it in to my XtraDrive (turn your SD/ MMC memory cards into USB Thumb Drive) and turned it into USB Drive and pluged in to usb port and did low level format with HDD Low Level Format Tool 2.36.1181, may be letest version is there on website (HDDguru). After low level format i went in to manage by right clicking My Computer and formated with FAT32, removed USB drive and pluged SD back in to Slot and it was Working

Hope this may help someone