Can I do it?

Yes! There is a way to recover deleted content, even grades from a deleted assignment.

How do I do it?

Click "Home" from the course menu.
In the Internet browser address bar, insert your cursor at the the end of the course web address (ie. https://btc.instructure.com/courses/1899141).
At the end of the web address enter a forward slash (/) and "undelete" (ie. https://btc.instructure.com/courses/1899141/undelete).
Hit "Enter" (PC) or "Return" (Mac) on your keyboard.
On the "Restore Deleted Items" page, there will be a list of items that have been deleted from the course.
- Click the "Restore" button for items that you want restored to your course.
Items restored to your course will be Unpublished. Publish and add the items into modules, as needed.
- If the restored item is an Assignment that has already been graded, you MUST publish the item before grades will be added back to the grade book.

For more information, check out the Canvas admin blog post Undeleting things in Canvas.

The "Undelete" function is not supported by Canvas and does not have a 100% success rate.