Did you purchase an item on eBay and paid for it on PayPal?
If not received, you should contact your seller and ask when and how it was shipped.
The procedure here is very simple:
If you are not satisfied, then you should file a claim with eBay: http://pages.ebay.ca/help/buy/item-not-received.html
Just follow the procedure.
Finally, if unsatisfied with the seller, you should leave appropriate feedback.
http://pages.ebay.ca/help/feedback/allaboutfeedback.html
Currently, your record shows you have yet to do so.