If tracking shows delivery, but nothing arrives, contact the shipping service to determine if the tracking corresponds to a delivery to your address.
If you can obtain hard copy documentation of that the tracking does not correspond to a delivery to your address, contact eBay via social media and explain that you have a case of "false tracking" and you should be given the opportunity to provide your documentation to eBay via direct message. This is different than the usual "item not received" case which is handled automatically and which allows the seller to win by providing tracking that shows delivery.
You can avoid many issues entirely by choosing to only do business with experienced sellers that have a proven track record of delivering similar items as seen by examining the seller's feedback page, and by avoiding inexperienced sellers, sellers with patterns of negative feedback indicating serious problems, or sellers with large gaps in the selling history or recent drastic changes of seller behavior.
