Audacity does not officially support Windows 10 yet.
Audacity requires audio drivers it can use. The first step is to go to the web site of the computer manufacturer or motherboard manufacturer and see if you can find the latest audio drivers for Windows 10 meant for your specific computer. This is a fluid situation, so also using Windows Update and trying to update your sound device drivers from time to time within Windows Device Manager may be beneficial.
If you are using external sound devices or interfaces, ensure they have updated Windows 10 drivers and firmware. Disconnecting external audio device might help Audacity recognise the drivers of the built-in device.
If that does not help, please see https://forum.audacityteam.org/t/internalportaudio-error-since-windows-10-update/39286/1 for other solutions.
Gale