Apple ID changed post upgrading to iPhone 15.

I upgraded to iphone15 was locked out had to change my Apple ID email to one that was used in 2022. My email attached to iPhone15 can not be accessed at all. So I can not find an iCloud back up after 2022. I lost several voicemails from my grandmother that passed last year. Can I retrieve these some other way? I talked with my carrier they can not access visual emails. Pls help

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