I'm using Samsung S Duos 7582. My phone was hanged and i restarted it , after that the pictures in my device storage and SD card is not visible in Gallery. And not able to select the mp3 songs as my ring tone, I've restarted the mobile device many times. But no change , kindly suggest.
It seems your SD Card has been corrupted.
Here i will suggest check with another device so it will be clear that what's the main problem.
Check whether your memory card got corrupted. If it is not so then copy contents to your computer and then format the memory card with your phone... Again copy contents from your computer to card .. Now it should work...