The buyer confirmed ordered and paid but I did not receive any notification
If they showed you an image with a confirmation page, it's likely a scam. Don't give them your email. Don't follow any links they send you.
You show no sales in your shop, so there is not in fact any confirmed order.
You have 0 sales in your shop. Any message or notification is most likely from a scammer.
This happened to me yesterday too. An item was marked "Sold Out", buyer mentioned they had paid, but I never received order details. I contacted ETSY, but they couldn't help without an order number (Catch 22).
Did your buyer get an error during payment? Do they have a receipt? If not, you must renew the listing and pay the extra fee, then ask buyer to re-buy the item. That worked for me.
I don't think this is a scam but simply another Etsy bug. Paying the extra renewal fee was off-putting though.