Downloaded files are repeatedly deleted

[infected78]

Hi, since 2 weeks ago every time I start my PC and Spotify launchs, it kills every file on my smartphone (Iphone 6 plus, IOS 10.3.2; Spotify 8.4.8.467) which I downloaded from Spotify.

The space is still used and I even can listen to the Songs offline as far as the songs are in the currently used playlist, but I can not change them to other Albums or even download them again since the Buttons are grey/jammed, so that I have to delete the Spotify App in order to be able to download the albums again. Is there anything i can do to prevent this from happening?