Hello @cmroach ...
Any assignment listed in your Gradebook would also be listed on your "Assignments" index page. Do you see the assignment listed on your "Assignments" page in your course? If not, then it may be possible to get that assignment back by using the hidden "undelete" trick. Check out Undeleting things in Canvas by @hollands. Hopefully this will help you out. Let Community members know if you have any other questions about this...thanks! Take care, stay safe, and be well.
