What do you do when a book has been sitting in the post office for 2 weeks? The tracking on a book sent to me still just says, " book accepted at post office".This particular book was sent postage paid through PBS.

I have another book that was sent and the sender sent me the tracking number that day. It is also delayed by 2 weeks and still says it is on the way to the next facility. This one is coming from a rural town in my state. 

Like everything else, I think the post office is understaffed. You could try the USPS site. There might be a contact form or number.

Go to USPS.com.  There is a Contact Us button near the bottom of the home page.  Use that twice - once for each book.  It generates an email to the Supervisor at the last station where it was actually scanned.  They have (I think) 2 business days to either respond to you or forward it on to the next location.  It does work quite oten.  Sometimes a container of parcels gets put in an area where it isn't really supposed to be.  Those sorting centers are humongous!  This type of email can get someone to looking around and trying to find out what happened, and getting things back on track.