I lost all of my decks due to inactivity as I couldn’t read the email regarding deletion of my account, due to the fact that I couldn’t login into that mailbox.
I don’t have any backup nor on my pc nor on my phone as it was quite a long time ago.
Is there a way to sync them back from my last activity?
Normally when your data is removed, that includes all server-side backups and AnkiWeb has nothing left. In your case, one of your server backups is still available – from January 2024.
Please confirm if you want me to restore than to your AnkiWeb account. It will overwrite whatever is there, so if you have other data on AnkiWeb or on your synced device that you want to save, make sure you preserve that collection first. [See the link already posted about how to merge the collections together after syncing.]