How can I restore an assignment, including student submissions, grade and feedback via Speedgrader, that was deleted in error?
Welcome to the Canvas community, Les Edinson!
While I'm not sure if it will restore submissions, you can use the "Undelete" page to restore deleted materials. Shaun Holland wrote a nice blog post about it.
You can't use it to recover some things, like external URLs from the Modules page, but it can do big things like assignments, quizzes, and files.
Retrieving data ...