If you download a solution with nuget packages installed but the reference is not resolved pay attention to the packages folder.
Usually the packages folder contain a subfolders with dll and xml for each installed packages.
Sometimes when you download a solution from web does not contain dll but only xml.
To get the all right dll
If there is already a folder “packages” with the subfolder packages, delete it, otherwise nuget will notfy that the packages are already installed.
Then go to your project folder where the file packages.config is located
Go to nuget site and download nuget console (I place it in c:\tmp\nuget.exe).
Execute this command in the command line and all the missing packages will be installed correctly
C:\mysolution\myprj>C:\tmp\nuget.exe install packages.config -OutputDirectory ..\packages