Hello @NReynolds 

Thank you for contacting the Instructure Community. There would generally be two ways to recover grades for the student. First, you could try going to the beta instance if these changes were made sometime this week. Beta will show the course from this past Sunday and you can export the gradebook as a csv, then remove the other students and import the grades back in the live instance as long as the data for the user (section ID, etc.) are corresponding correctly with their current data. Or, you can see about putting the student back in the original section in your SIS and running a sync. This should also bring the grades back that they had and you can either export these, save them, etc. and manually enter them once you switch the student back. There are likely other alternatives but you would maybe want to speak with CAMS and/or Canvas directly. Hopefully this helps.

How do I contact Canvas Support? - Instructure Community