I've screwed up. I sent my Time Machine Backups.backupdb folder to the trash.
Fortunately, I caught the error and didn't empty the Trash and dump the folder.
You can't. Once removed from the Backups.backupdb folder, backup folders can't be put back:
Unless you need something from it, move the "Retrieved" folder to the trash and empty it (while holding the Alt/Option key).
Or, if there's nothing left on the drive (not a good idea to mix other stuff with Time Machine backups anyway), just erase it with Disk Utility.
I spoke too soon, something's not working right. I sent the "retrieved" backup folder to trash, but the original folder on the HDD is empty, plus now I can't see anything in TM, and I can't even open the TM preferences.
And I can't empty trash because the backup folder will not be deleted. What now?
. . .
the original folder on the HDD is empty
That's how it looks, because everything is in the (hidden) trash folder there.
now I can't see anything in TM
Correct. You deleted your backups. There aren't any to display.
I can't even open the TM preferences.
That's curious, but will probably work after the trash is emptied.
And I can't empty trash because the backup folder will not be deleted.
Did you hold the Alt/Option key while selecting Finder > Empty Trash... from the menubar?
If so, exactly what was the message?
Thanks again. I didn't know that you could empty from the Finder menu bar, I've been right clicking the trash and emptying from there, but whatever the difference it solved the problem. And while I was sitting thinking dark thoughts about Apple, Time Machine went ahead and did a full backup so now there is "stuff" in there to see and it's working as expected.
Too bad I didn't read your informative home page on TM before I screwed the pooch, but I do have most data files scattered around in various backup forms including dropbox, so it could have been worse. And I took your advice and moved everything off the HDD except backups.
Thanks for the help,