Summary
How to see all the historical Support cases created for Marketo
Issue
How to see all the Marketo Support cases, attachments, and comments related to your historical support cases
Environment
Support Portal
Solution
Authorized Contacts can see the cases that they personally created/own, and the Support Admins can access the all cases on the entitlement from within the Support portal.
Below is a community article with additional information and instructions:
Managing your Support Cases