My local files have disappeared from my IPad

[leefoo]

Plan

Premium

Country

 USA

Device

IPAD Pros

Operating System

(iOS 11

My Question or Issue

 I had hundreds of local files from my computer on my IPad. Last night I went in to listen to them and they are all gone. Any idea on how that could've happened? I am currently trying to re-download them, but that shouldn't have happened, right? Is there any way to prevent this from happening in the future or was this a freak occurence?

Thanks
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Update 30 min later....downloading failed. I have no Local Files on my IPad and I have no idea now how to do it because the normal way failed.