Files disappearing from Sd card

[KOTA-JS]

I am using Experia E4 dual from past 2 years 9 months. Since last 6 months I am experiencing a problem i.e. sometimes all my files stored on SD Card were automatically diappearing. Sometimes pics, sometimes music, sometime pdf files. Is there any solution and why its happening. Files stored in phone memory are perfectly OK but it disappears from SD card.

[Uliwooly]

@KOTA-JS

If you test the SD card with other phones and/or your computer and you can't find the files, you should back up EVERYTHING on the SD card with your computer ASAP, as you have a faulty SD card and could corrupt everything.