I sure hope it wasn't expensive. You must never wait longer than day 45, - though day 43 is the 'best last' day to file a claim. It would seem you have seen this link about what to do when an item never arrives:
http://pages.ebay.ca/help/buy/item-not-received.html
What the link does not tell you is that if you are promised a replacement, if that too does not arrive no later than day 43, - file that claim. If you are told the most earnest promises from the seller that the item is on its way, please be patient, yada-yada, - do not let yourself be delayed past day 45. If you are told the refund is 'on its way', or is 'being processed', there is no such thing as refund notices are sent instantly. Sellers in a 'certain few' (very few, in fact, I can think of one) countries are adept at sweet lies of delay.
If ever you open a claim, do not close it until you have either your item or your money. A closed claim can never be reopened.
You have 60 days to leave feedback. If you can express your thoughts in a relaxed and intelligent manner, you will more likely be believed by others. The seller may respond with more lies, but you can then reply with the third and final response.
As for your money back, - unless you used a credit card and can inquire with your card company about a chargeback, there is nothing you can do. If the chargeback is an option, do it now because there are deadlines for that too.
In future, when that reminder note appears on the listing in your Purchase History, - the one that says "If there was a problem, go to the Resolution Center by day/month/year", - take it seriously.
