I have a Dell Inspiron 7520 and a Dell D3000 docking station connected through the USB 3.0 port. Before updating to Windows 10 (I was using Windows 7), everything worked fine. Two monitors were connected to the docking station (one through the HDMI and one through the DVI port) and my laptop used all three displays just fine.
After updating to Windows 10, no monitors that are connected through the docking station are detected. The monitors are detected if I plug them directly into the laptop's HDMI or VGA ports. However, other USB devices (e.g. keyboard, mouse) still function properly through the docking station. Only the display monitors seem not to be detected.
I upgraded the driver for the D3000 to the most recent one (here). But this did not help.
Best Answer
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.