When cleaning up a course import for next semester, I accidentally deleted an already graded assignment for my class and I need to recover their submitted work.

I already know and have already done  /undelete at the end of my course homepage url and the assignment did go back into the course, but just as an assignment item in the gradebook. It is missing the students' submissions! It just went back in as an assignment, but no prior submitted work for those students. I need to see their work. How can I retrieve???