Game Crashes or stays loading forever

kyuumihaira​  That means that something in the folder you moved is the issue.  So you'll need to test any files you'd like to keep in the new Sims 4folder to find the issue.

If you want to restore your mods and cc, test those first, either in batches or using the 50/50 method:

https://modthesims.info/wiki.php?title=Game_Help:Finding_Problem_Custom_Content#The_50.25_Method

Once you've done that, you can move over the contents of the saves and Tray (saved households and builds) folders, plus Screenshots and Recorded Videos if you care about those.  The rest can be discarded.

One note is that some mods place files in the saves folder, so look out for that, especially if you're removing or replacing the mods that are creating those files.