I'm sorry to hear you're unable to revive funds sent to you. When a payment is completed, you will see the money in your pending or available PayPal balance. If the funds are not located there, we recommend to not provide the product or service until you see the transaction on our official website.
Did you receive the notification by email? If so, here's an article from our Help Center that explains if an email is from PayPal. I hope this helps!
