Somehow lost all of my music folders on my USB

I was recently trying to tidy up my collection on Engine DJ and decided to create a new USB. On that I put one folder of about 270 tracks. However somewhere along the lines my actions have removed all of the other folders on my original USB? Having used multiple platforms (Traktor, Rekordbox, Serato, etc) I have never had this happen before in over 5 years. I had seen a couple of posts about losing tracks but didn’t think that I had done anything odd.

I believe the majority is backed up and I am hoping I can re-download a fair amount, but still quite scary that this happened without me even realising.