…and now every new project tries to find c_sky_horizon_color1 which doesn’t exist (I did backup the original). I do have the original .uasset but it doesn’t appear in the content browser. All in all, I would like to completely reset Engine files since I messed with them for experimentation but I thought it changes them on a per-project basis, not the actual template files.
Reinstallation the only way?
Epic Games Launcher → Unreal Engine tab → Library → Engine Versions section → Click the arrow next to “Launch” → Verify
Alternatively if you built from source, you might rerun setup/re-pull from master.
Secondarily you could manually search through and rename the asset. Also make sure your view preferences include engine content.
Thanks! I actually tried this a few minutes ago, it just finished and it now works like a charm 
Never again “Engine Content” enabled!
Hey, engine content is amazing. A lot of good assets exist there, and I always include them when I grey box a project. Just be careful not to modify them without creating a child object that exists in your project 
As a beginner, I’ll make sure to not touch these things unless I know how to work with them! I thought I’d have to redownload the entire engine (lots of waiting with my current connection)
Actually I used to deal with that when I only had a 1.5mb connection. If you have the hard drive space, do a manual copy of the clean engine install as a backup. Secondarily setup GIT for your project so if a crippling mistake is ever made, you can roll back in an instant.