Lost second display following an update

[wingnut75]

An update was applied sometime, although I'm having trouble finding what was installed, about two weeks ago. The laptop booted through bios updates and something else.

Following that update I am no longer able to detect a second display. I have 3 different monitors I had previously used within a week prior to whatever happened. I have a usb-c dock that everything else works on it, usb mouse, poly headset etc... but the display doesn't. The display also doesn't work if plugged in direct.

I have tried reinstalling the latest display drivers, updating the bios again to see if this would resolve the issue but nothing so far has worked. I have fully powered the machine off. I do not have the option to remove the battery. This step as I've seen suggested in other posts also has not yielded a fix.

Please help, the extended display is a function I use regularly almost exclusively on this device.

[wingnut75 · Accepted solution]

Since there were no replies here, I subscribed to HP Smart Friends for assistance. The tech told me to power off the laptop, Hold down Windows+B and power it back on. This went through a BIOS reset. The machine restarted several times with a firmware update message being displayed on the screen multiple times. When the process was completed, and I logged back int the laptop my external display was working again. 

The tech stated that it's possible that the BIOS update previously installed did not complete properly or something. In any case, I have my external display back and I and use my laptop again.