Hey there, @Kay_IIB
Bo here from Shopify Support!
I am sorry to hear you are in this situation, I can imagine how stressful losing a domain can be. I will be reaching out to you via email directly to authenticate you as the owner of the account and get the appropriate team to look into this and update this for you. I will need you to respond to that email directly confirming the myshopify.com address of your store as well as some other authentication information as per my email instructions and I will then be able to see about manually renewing that domain for you.
When it comes to time-sensitive, account-based issues it is always best to reach out to Shopify Support in a more direct manner. If you go to this page and click Contact Support you will be prompted to either login or continue without a store. Once you have selected an option you will be asked to ask about a topic. Search for your query and relevant help docs will populate as well as the option to proceed to live chat or email. I’ve made this quick video here to show you how. You can also reach our Support team @ShopifySupport on Twitter or through Messenger on Facebook here.
All the Best,
Bo | Retired Staff Member