the Macbook Pro would not even detect the external monitor.

My Macbook pro will not connect to an external monitor after moving it. It has been running on this same monitor for 8 months. I switched to a new Desk last night, after hooking it up, the Macbook Pro would not even detect the external monitor. It was only showing the Macs monitor in Display. It did not even have where you could "Detect Display" available. Is there an update that I may have missed. I have tested all the Monitor connections with another laptop they all work.