Lost Nokia Touchscreen Phone

On Fri 18th Jan I left my black nokia lumia 800 phone in a taxi from Harcourt Street to Cabinteely although it may also have fallen out on Harcourt street prior to this. When you try to turn it on there is a four digit pin code for the sim. It may have no battery though as it was turned off when I tried to ring it. It has silver buttons on the right side of it and two sections for usb and sim card on the top.