Go to-> My eBay (top right of this page)
Go to-> Purchases (left hand column)
Your purchase should be there.
If it is not, go to the credit card you used to pay and phone Customer Support (number is on back of card or on monthly invoice).
Ask about a chargeback.
You should have 120 to 180 days from Payment to make a chargeback for Item Not Received.
If you used Paypal as a payment processor, go there after eBay and before the card.
EBay won't act if you have started either a PP or a cc Claim. PP won't act if you have started a cc Claim.
The card is the last appeal of the three.