NuGet is free, open-source package management system designed by .NET Team for the Microsoft development platform to ease the task of integrating any 3rd party open source components in the project. NuGet has changed into a very big ecosystem of tools and services after it was introduced in 2010. NuGet is most commonly distributed as an extension in Visual Studio.
First enable package restore as mentioned below:
Try updating your Visual Studio to the lastest version, sometimes the updates helps you solve package issues which was previously not supported.
Right-click on the Solution and click "Restore NuGet Packages" option. Or you can try executing this console command in the folder that has your solution file:
Try removing all the nuget packages. To do that, select NuGet and then right click to remove it, then go to the app package and remove the Packages Folder. After doing this just restart your visual studio (VS) and reinstall the Nuget Packages again.