Hi @swmcneill,
Whether submissions for old courses still exist and are accessible to you does somewhat depend on school/institution policy and how they have Canvas configured. If you see the course on your dashboard or in your All Course area, you should be able to go back to your assignments and find the submitted files there. If the course is no longer accessible to you, you may be able to look in the submissions folder in your user files area to see if the files exist there. If neither of those things work, your files may have been removed, but you could contact your school/institution Canvas team (usually in the eLearning / IT / Digital Education areas) to verify that.
Please do come back and let us know if any of these methods were successful!
-Chris
