I work in IT for a small company and recently one of our users had the same issue. If you open device manager do you have any display adapter drivers that have stopped working? If you have an Intel driver that has stopped due to a problem there may be a work around.

We found that if you opened the laptop lid and then restarted the computer, the external monitors would identify and work. You could then close the laptop screen and continue working but whenever the laptop is turned off or undocked it would need to have the screen open in order to identify the monitors.

This is by no means a long term solution but it seems like this is a problem with Win 10 and will hopefully be fixed in the near future. I haven't tested it yet but I also so that Nvidia pulled their driver from last week due to some display issues so maybe that was the problem. Hope this helps.