Apple added an option in late 2016 to give you the equivalent of cloud-based bottomless Desktop and Documents folders in macOS to pair with iCloud Music Library and what’s now called iCloud Photos. In the iCloud preference pane, you can click iCloud Drive and then check the Desktop & Document Folders box to enable a sort of provisional sync.
If your Mac starts to run out of local storage, macOS will delete files from local storage based on the oldest files with the least use, ensuring that a copy exists in iCloud Drive. If you need the file back, you can just click it and it’s automatically restored. You can also find all the contents of Desktop and Documents folders via iCloud Drive from any Mac on which you’ve enabled the feature.
However, the transition between using this bottomless folders option and disabling it remains confusing to users years later. (I wrote about some of the drawbacks in early 2017.)
When you uncheck the Desktop & Documents Folders box, it appears as if all your files in those two folder locations are deleted—they disappear!

The Desktop & Documents Folders setting can be accessed on the Mac via System Preferences > iCloud, then click the Options button for iCloud Drive.
Never fear. They remain in place, but in iCloud Drive. Use the steps below to restore your items to their original locations.
(Note: If you want to remove the copy from iCloud Drive as you restore your files, hold down the Command key while dragging, which is the equivalent of “copy to new location and delete from old location” instead of just “copy to new location.”)
Open iCloud Drive (in the Finder, select Go > iCloud Drive).
Open the Desktop folder in iCloud Drive, select Edit > Select All or press Command-A, and then drag or Command-drag the contents onto your Desktop.
Open the Documents folder in iCloud Drive, select Edit > Select All or press Command-A, and then drag or Command-drag the contents into your home Documents folder.
If you find multiple Desktop or Documents folders in iCloud Drive, this is due to having enabled the sync feature on multiple Macs. The first Mac with which you used the feature names the two folders simply Desktop and Documents. However, any subsequent Macs add the name of the Mac at the end of the Desktop and Documents folder names.
This Mac 911 article is in response to a question submitted by Macworld reader Katia.
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