Thanks for the question and as you have reached the German community - wir können das gerne auf Deutsch weiter besprechen wenn du möchtest. But English is fine too.
Have you managed to contact support about changing the ownership of your shop? If not, please send an email to our support here (https://bit.ly/3cwO7ym) from the email address you use to log in to your Shopify store, and enter your myshopify.com URL there as well. Once they authenticate your account, they can help you out.