Why is my purchased domain not linking to my store?

My shopify purchased domain is not connecting to my store. I may have done something wrong in the initial purchase or connection. I did have a practice store that I closed and am thinking that it may be connected there. But I cant get back in to the practice store to transfer it? pls help

I recommend you to email directly to Shopify’s Merchant/Technical support. They should assist you with the issue!
Contact page link: https://help.shopify.com/en/questions#/contact/email