Automatic deletion of files and apps not installed on Lumia 820?

[Windows Central Question]

automatic deletion of files and apps not installed on lumia 820

i am using nokia lumia 820, from a week when i add some new music or image files to my sd card and phone storage which is my default storage the files i added are automatically after some time and i i delete any files they are reappearing automatically. this creating a quite a problem to me. And new apps and updates are not installed.
can anyone please give me solution for the issue?