“I have an lg optimus G and i took the sd card out but when I put it back in, all my music and photos had disappeared! All my apps came back that were on my sd card and one folder in my gallery which is called ‘sd card’ but everything else is gone! :-(
You can view the SD card files from your computer, I guess. The reason is that your Gallery App can not find the path where the music and photos are stored.
You can solve this problem by delete the “Media Storage” App’s Cache and Data:
1) From home screen
2) Press Menu-> Settings
3) Application Manager
4) You will see 3 menu at the top of your device screen, Download, Running, and All
5) Tap “ALL”
6) scroll down slowly and locate the “Media Storage” App.
7) Tab “Media Storage”, You will find the “App info” screen
8) From “Media Storage” App info screen, Tap, clear data, and clear cache.
9) Reboot your device. About 10 min. later, You will find all photos back in your Gallery.
Wish this Helps