"I have not recived my item and ebay dont help me"
Did you notice the LAST ESTIMATED Delivery date on the listing?
Did you look at the seller's poor feedback before buying the item?
Have you noticed the eBay Money Back Guarantee on the listing?
Why did you leave negative feedback before the transaction is complete?...that will not make the item arrive or lead to receiving your "MONEY BACK".
Perhaps in the next few days if the item has not arrived you should open a case for Item Not Received in the eBay Resolution Center & follow all instructions.
eBay WILL help you however you need to make the effort to protect yourself.