Join Date: Mar 2010
Location: Sacramento CA area
If the seller is someone known here, and hasn't responded. It may be that you are not the only one messaging him about a lost package and your pms are getting sucked up in the mayhem. Chances are he is trying to get everything situated and corrected not only with you, but others as well. I would suggest e-mailing him using the paypal information provided to submit an inquiry if you have not yet.
I would give it an additional few days, Tuesday the latest, for a response from the seller. If by then the seller has not communicated to you via e-mail or pm, then you may open a dispute with paypal. However, if he has original receipt of shipping, then you won't get the money back.
Given we are a close knit community here, I would give time.