These topics:
https://forum.audacityteam.org/t/internal-portaudio-error/39275/1
https://forum.audacityteam.org/t/internalportaudio-error-since-windows-10-update/39286/1
have some possible workarounds including trying manufacturers’ audio drivers for Windows 7 or 8.1, rolling back to Microsoft audio drivers, trying generic Realtek drivers (if you have a Realtek audio device), or using Audacity 2.0.2 or 2.0.3: http://www.oldfoss.com/Audacity.html.
If you have any external audio devices you could try unplugging them to see if Audacity will then see the built-in audio device.
You could also try restarting the computer. This may prompt more Windows updates to take place or may just solve some flakiness somewhere. I was getting the Internal PortAudio error on Windows 10 when I was experimenting with Windows 8.1 audio drivers (no Windows 10 audio drivers are available yet for my laptop) but now Audacity recognises those 8.1 drivers.
Of course, if Windows 10 audio drivers appear on your computer manufacturer’s web site you should use those. Failing that, trying to update the sound device drivers every day in Windows Device Manager using the option to search the internet may possibly help. You might receive some tweak to the audio drivers Windows 10 originally updated to that will get Audacity to recognise your audio device.
Gale