Board Thread:General Discussion/@comment-79.76.72.76-20190825111417/@comment-39851000-20190825120138

You can contact MyTona and give them your old game ID (same as your friend/invitation code), and they can restore your old game for you.

If you don't know your old game ID, you can still try contacting them with just your old game name, there's a possibility they can help you, but no guarantees.