It's very likely that your seller will not see your message here.
You need to be proactive for yourself, a process that eBay has made automated.
In the listing where you made your purchase, you saw an estimated delivery date. If/when that date has passed by more than a day or two, you can open an item not received case.
PLEASE read eBay's Money Back Guarantee for buyers, seen in every listing, to learn how this works.
