what to do if post office lost package?

[vansen19]

i sold a mama a large meaf cover right before xmas but shipping info shows it's still at my city's PO! i sent her another cover to tide her over after she contacted me 2 weeks after payment (i felt so bad).

do i call the post office and try to pick it up? do i refund her payment and just say goodbye to the cover lost in shipping? i still have the DC #, and i don't like navigating the USPS website, their terminology etc is a bit confusing.