This is a member to member Board, and is rarely seen by eBay employees.
You bought something.
You paid for it with Paypal.
It did not arrive.
You contacted the seller.
The seller promised a refund.
There is no refund in your Paypal account.
Is that right?
Do you back your PP account with a credit card? If so look in your cc statement. Such refunds show up there not in your PP account.
When did you order?
Did you open an eBay Dispute?
You can open a Dispute for 30 days after the last estimated delivery date.
What was that estimate delivery?
The Resolution Centre is at the bottom of this page.
The first suggestion is to Contact the seller. You have already done this , so escalate to a Claim.
If the seller does not prove delivery (not shipping, delivery) you will be refunded.
If the deadline has passed, come back for your next level of Buyer Protection.