AnnaI This is a “ how long is a piece of string” question; of course you should be able to do this, but it depends heavily on the design configured for you solution!
By “Support Case” I’ll assume an Incident.
Check if you have an “Incident Search” query in your UI as we would typically setup with a prompted query you can use to search across various parameters. If you are using the Workspaces frontend that would typically allow you to filter Incidents by ”in-column” filtering too.
You could search based on “Creation User” or “Company” perhaps depending on what search facilities the query has defined.
Either way though you don't give much information to go on right now.
I believe you are referring to Ivanti Support? If yes, then you can ask them for the case number and any required details. Or you can just ask them to assign you the case itself. I usually do this when someone from our team is on leave or so.
piece of advise: create one shared mailbox and use it for support matters (like raising cases with Ivanti) so you don’t run into such issues in the future.