I originally tried an upgrade from Win 8.1 to 10 last month, and ran into the same issue. I didn't see any official resolution other than some forum posts with some workarounds, which I didn't want to do as I can only assume down the road those workarounds will be an issue. So last month I rolled back to Windows 8.1 for now to continue using Workstation 12.
This weekend I decided to upgrade to Windows 10 again, and what I did BEFORE upgrading is a complete un-install of Workstation 12. Then I installed from fresh after my system was upgraded to Windows 10.
Unfortunately I'm having the same problem.
I tried the Virtual Network Editor -> Restore Defaults (just hangs for a very long time but never creates the virtual NICs)
I tried going to my Network Adapter in Windows, going into Properties > TCP/IP v4 -> Install -> Service > VMWare -> VMWare Bridge Protocol. I get an "Access Denied" error.
So what is the solution?
I did an upgrade from Win 8.1 -> 10 yes (rather than a fresh install of Win 10) but did this without VMWare Workstation even installed, so it shouldn't matter that this was an upgrade and not a fresh install of Windows. It's a new Windows folder, new install of Workstation.
Is the only solution to do a fresh install of Windows just to get Workstation working? I really didn't want to have to re-install ALL my other programs and settings. There has to be a better way.