First step- if you have not already contacted the seller, do so. There is a button right on the listing.
Ask for the shipping date, shipping service and tracking number for the item. Don't worry if there is no tracking number.
If the seller does not answer or if he offers a replacement (which will never arrive either, btw), go here:
http://resolutioncenter.ebay.ca/
Open and Item Not Received Dispute.
The first step there is to contact the seller, but you will have done that. Go to step two and escalate to a Claim.
If the seller does not prove delivery, he is required to refund you.
Again, do NOT accept an offer of a replacement. You want your money back.
If the seller does not refund promptly, Paypal will refund you and go after him hard for their money. He will not like that.
You will not be able to leave feedback.