Files lost after High Sierra (10.13.4)

Hi there,

So, a few days ago (after postponing the update for a very long time) my MacBook Air Early 2014 decided to update itself during the night - fair enough. The only reason I noticed the update had gone through, was because my wallpaper had changed by itself. I found this a bit strange, so I went to change it back to the one I had prior to the update.

I had a separate folder for all wallpapers I'd had for the past two years or so, but the folder was now empty. I figured it was just some glitch in the Matrix, so I rebooted my laptop.

After rebooting, the folder was still empty. I started to check other folders to see their contents, only to find those empty as well. After scouring my laptop for a bit I found that 70% of my photos are gone, all my movies are gone, ALL of my school work is gone, as well as several applications I'd installed in the past month or two. No problem right - just use Time Machine or some iCloud backup?

Apparently not. No previous records of Time Machine exists, no backup on iCloud, nothing. Now, my school work is not super important seeing as a graduated four months ago, but all my photos and movies are nowhere to be found, and seeing as there's no Time Machine backup to find either, I'm not really sure what to do..

Has anybody had this issue before, and if you succeeded, how did you recover your files?