Eunice here from Shopify, thanks for posting, and welcome to the Community!
Did you hire a Shopify Expert through the Experts Marketplace to help build your store? If you did, then I recommend checking out the Handling Disputes page from the Shopify Help Center. This page includes information on lodging a complaint and requesting a refund.
If you didn't hire a Shopify Expert, and you're unable to contact the third party then I recommend getting in touch with your bank to discuss your next steps. They might be able to retrieve your funds, or at least help you with your next steps.
Do you feel comfortable with building the store by yourself? I understand it can be overwhelming at first, but we have some awesome resources to guide you. Check out our free 'Getting Started' course by Shopify Learn. With this course you'll learn how to design and launch your store, as well as create happy, returning customers.
I hope this all helps. If you have any questions please thread those here.