I would contact your PO, although there is probably not much they are going to be able to do. They maybe able to track it but since there was most likely not insurance on the item, it will not be high priority for them.
*sigh* I know this is not going to be the news you want to hear but in the event she opens a case against you, she will most likely win, unfortunately. And that is because that tracking number shows it is in limbo
I guess it is going to be up to you on how you want to handle it. I would probably try and reassure her that it has been sent and send her the tracking number again. I suppose you could ask her also what she feels like a fair outcome would be?
I just want to make sure though this is for a domestic purchase, correct?