I know it seems unlikely/stupid, but I just restarted my computer to find that I no longer had a data folder. As of now Steam is redownloading all the files and I'm sorta pissed off. I remember trying to launch the creation kit and skyrim, and no programs would respond, so I reset my pc. If I deleted the data folder, I would have noticed the huge amount of files in my recycling bin. I've also been working on a few mods that I was stupid enough to not have backed up.

I did at one point in time sync my files to the steam cloud, is there any way to download those files?

How could this have happened?

I'm also very thankful skyrim saves the save data out of the steam folder

It wasn't caused by Steam or Skyrim, could be something wrong with the HDD though causing data loss.

Wouldn't my most recent data changes have been lost, and not the whole data folder?