Hopefully you put Delivery confirmation or Insurance on it so it can be tracked. The post office can track it more completely than you can online. If there is no tracking or it isn't helpful, then ask them to send an inquiry to the MRC (mail recovery center). They have to do it for you. You will need to give them as much information as you can about the item. They can even attach a photo of it to the inquiry. If they give you a hard time about filing the inquiry, tell them you know a postmaster (me!) and that is what she told you to do.