The Undelete Trick
If you accidentally delete something in your course, you can try to restore it by using the undelete trick.

Simply look to the URL bar on your browser, locate the 6 or 7 digit number after “courses,”
delete everything after that, and type /undelete
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You will then see a list of the 25 most recently deleted items. Clicking an item’s corresponding
Restore button

The list is limited to the last 25 deleted items.