On the docking station cable that plugs into your computer, unplug that and then take the USB type A end (looks like the end of a thumb drive) and pull that over the USB C (round connector) end. Once the two are connected plug the USB end into a normal USB port and that will reliably send a image to the external display. Please note that you will have to use your portable computer charger as this plug will not provide power to the machine. Below circled in red is how the end of the docking station connector should look like.
Once you plug the USB type a into the machine, you should get your external display back.