before ordering it again?  I have a book that is 2 days from the "contact pbswap" that I have not received yet.  And another book that the sender says they received the wrapper returned to them by the p.o.  So, I don't think that book is likely to show up without a wrapper!  So, how long should I wait before ordering another copy of these 2 books?

Carol, Here is a link from the Help Center about lost books.  Also, here is another about what to do when a book that has been declared lost is finally received.

Basically, you would want to PM the sender and then wait a while just in case it was mailed late.  However, on the case of the wrapper that was returned to the sender, let it go lost, you'll get your credit back and you can order another one or be back in line on the WL for it (as the help documents above state).  :)

In general, I wait a couple of weeks.  Most of my lost books have shown up a few days after they went lost.  If it were coming from Alaska, Hawaii, or an APO address, I'd wait longer.    But in the case of the returned wrapper, well, Amanda has said it pretty well. :-)