Cortana is your cloud-based personal assistant that works across your devices and other Microsoft services. Depending on the capabilities of your device and the version of Cortana youâ€™re using, Cortana can provide a range of features, some of which are personalized. Cortana on Windows is available in certain regions and languages. If Cortana isnâ€™t available for your Windows device, you can still search for files on your device in the search box on the taskbar. Cortana is also available on other platforms, such as Android and iOS, in select markets.
If Cortana is not working, then reinstalling the app package for Cortana and re-registering Cortana may help fix it.
This tutorial will show you how to reinstalling and re-registering Cortana for only your account (current user) or all users in Windows 10.