I'm not sure what happened, but we had a practice quiz set up in our course (which was essentially a course pre-assessment), and I wanted to "hide" that quiz from student view to make sure students did not refer to it for other assignments (specifically the upcoming post-assessment). I'm new to Canvas, and I naively thought that unpublishing this quiz would hide it. Now, it appears to us that unpublishing the quiz re-set all student attempts (i.e., erased all the assessment data), and we've now lost a lot of vital information that we were hoping to examine more carefully later on. Am I totally out of luck here, or is there a way I can retrieve any of this?
I obviously still have a lot to learn about Canvas, and I feel incredibly stupid right now. It shouldn't be so easy to erase assessment data.