This is Max from the Shopify Team.
Sorry to hear you've had trouble dealing with this shop. Shops are responsible for shipping and sending products to customers, so asking them for an update is the best first step. Usually, an email reply to your order details would be my first recommendation. I assume this has not worked for you.
If you placed an order with them and it was not fulfilled, then I would recommend that you contact your bank, or credit card provider (depending on how you paid) and give them the information about your purchase. They'll be able to give you the next steps for reporting and refunding the order if needed.
If you've also reached out to your bank, I'd suggest one other avenue for reporting a shop's behaviour for review. Head to this page and enter in a sentence like "I have a complaint about my order" here
Then follow the prompts to enter the relevant details. This is a good step to do last, as we aren't able to help with refunds or package tracking, but we can let our team know about your experience this way.
Ultimately, it's not an ideal scenario to lose out due to a shop being closed but I hope that information helps anyone reading this. We review shops in many different ways aside from the details mentioned here, but these steps are important for you to follow as a customer helping us track and report issues externally as well. I hope that helps you feel empowered to move onto next steps.