In addition to the advice that you have already been given, if by the time you started this thread more than thirty days have already passed since you purchased the item, it'll be too late for you to open an eBay case. However, if you paid via PayPal you have one hundred and eighty days from the date of purchase during which to open a non-receipt case against the seller via PayPal. If you do have to go down this route, though, make sure that you escalate the case before PayPal's twenty day cut-off date if it becomes necessary to escalate the case in order to get the problem resolved. PayPal tend to look at cases far more closely than eBay do, so if you do end up going down the PayPal route then you ought to receive a full refund of the money that you paid to the seller.
In the event that it's been more than thirty days from the date of purchase and you didn't use PayPal but chose to pay via credit or debit card then your next course of action would be to contact your card issuer and start a chargeback. Should you choose to pursue this option you have one hundred and twenty days from the date of purchase during which to do so, and you should stand a decent chance of securing a refund.
