Numbers Sharing Fail

I am the owner of a numbers spreadsheet. I am running a 2017 MacBook Pro with Ventura 13.7. I am unable to update my computer more than that version. I have always accessed the file from my computer. Now I need to sign on to iCloud to work on the spreadsheet. Today, I logged on as always, and got a message that the owner has not shared the spreadsheet with me. I am the owner. A co-worker also tried and got the same message. They have always had access in the past. What should I do? The only current copy of the spreadsheet is the one on iCloud.