Please click on "course results" from your dashboard. Then please utilize the search filter on the left hand side to match the below picture with "include past enrollments" set to YES. You can then search for a specific course, group, user, etc. Click "filter" then you'll be able to see the results of any past enrollments!
Things don't get deleted so even if it's a course you no longer have access to, you'll still always have access to the results.
You also have the option to export the results if needed for any outside record keeping. Click HERE to learn more!