How to find out why files disappear?

Question

linux

Lubuntu 14.04
ext4 partition. There is a folder with music. Files randomly disappear from it periodically.
How to find out what and why deletes / overwrites files ??
If it's important, I often download music via youtube-dl from youtube. And I also have a Windows dual block.

Answer 1

The section where you download, what file system does it have?
Although stop, let me guess - a Windows partition with ntfs?

Answer 2

The universal catch method is icron on Linux / procmon on Windows.