Hi  @michael_smiley   I have a quick question that may help folks here provide the most accurate suggestion.  How was attendance set up in your class?  Was it using Roll Call, an assignment you created and kept track of manually, a third-party software?  There may be different options available to you depending on how attendance was tracked.

However, you might try going to your homepage and in the URL field type in "undelete" at the end.  This should give you a list of recently deleted assignments.  If you look through this and see the assignment you deleted you can restore this and see if the grades return as well.  I just tested in my sandbox with a random assignment and it worked for me.

Hope this helps and best wishes!