MP3 FILES BEING MOVED TO LOST.DIR FOLDER

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Have you experienced saving some mp3 files to your sdcard particularly on 32Gb sizes that whenever you restart your phone those saved files are gone?

Actually they are not totally gone but are renamed and placed in your Lost.Dir folder found on your sdcard. 

As I tried to look out for solutions so far the only effective way to get rid of that being renamed and transferred to mentioned folder is by formatting your sdcard.