So....in my amazing luck with the Sims,
Today I downloaded S3PE to merge packages for my Sims 3 game. When I finished that and went to play my Sims 4 game, my Sims 4 game just never loads and I have to force quit on the program. When I went into my mods folder to see if a new cc I downloaded today was corrupt or something, I noticed all the Sims 4 cc and mods I had downloaded previous to downloading S3PE changed the file name to "Sims3 Package". So I took my whole Mods folder out, and I started to place sub-folders in one by one to check for a problem. It ended up being a corrupt file, but the change of the file name doesn't seem to affect my game.
How do I change the file name back if I can? I hate that it says "sims3 package".
I have Windows 10.
You mean that the description was changed. The file name/extension remained the same (package) to change the description back you can try installing S4PE that should do it. If not you must edit the Registry. You can get help in a Windows forum with that.