You have 45 days after paying for something to open up a PayPal dispute. Check the date of your transaction. If you are not beyond the 45 day limit, *immediately* open a dispute through PayPal. To do this, go to the "Resolution Center" on PayPal. There are tutorials and explanations that make this very easy to do.
Do not wait to open a dispute! I recently opened one just 10 days after placing an order because I had not gotten shipment confirmation from the seller and the seller had not responded to my email. Opening a dispute will "wake up" the seller to your problem. If they cannot send the item, PayPal makes it easy for the company to refund your money. If they do not close the dispute one way or another, PayPal may take action against them.
Edit: I noticed at the bottom of your post that the transaction date was July 13th. This means you can still open a PayPal dispute. Do not delay, however, as your 45 days will be up very soon.