1000 Files on my mac randomly moved to trash. "put back" doesnt work. What do I do?

Parts of the Finder window are covered, but I can see that several (maybe all?) of the files in the Trash have a cloud icon.

Don't go changing anything before reading through, and making a backup!

Here is what I think is happening:

1) You have activated "Documents & Desktop in iCloud"

2) You have quite possibly checked the "Optimize Mac Storage"

Number 1) makes it so your "Documents" and "Desktop" folders are stored in your iCloud Drive.

To confirm this, open a Finder window, click on iCloud Drive in the Sidebar and check that you have those two folders there.

Number 2) allows files to be removed from your mac drive if necessary to save space, thus keeping them only in iCloud.

If this is the case, you should first make copies of your stuff somewhere else, like an external drive, then possibly uncheck these boxes. I cannot overemphasize the need for a backup. Should something fail in this process, you could easily suffer data loss.

First, do a backup NOW!

As I wrote before, BACKUP is extremely important.

The message you showed is one to make one - justifiably! - worry about potentially losing files.

That is why, in addition to doing a BACKUP somewhere else, I recommend that before you uncheck that box:

make a new folder on your mac - call it, say "Documents-My-Mac" - and copy everything that is in the Documents folder to this new one. Likewise, for Desktop.

Then you can safely uncheck the box, knowing that the files reside on your mac, in folders that are not affected by the change. After disabling Documents & Desktop in iCloud, you can grab all those files and put them in the actual Documents and Desktop folders and all should be back to normal.

Make sure that the files you see in the trash are copies of what is by now in the proper locations, and you can empty the trash.

Oh... and did I say you should have a BACKUP somewhere else? 😎