Find the .nuget folder in your project folder. Sometimes when you copy the project you might be miss that folder because of its hidden in your project directory.

If you dont miss the folder and still you get the error, hope you can find solution from this link 

https://docs.microsoft.com/en-us/nuget/Consume-Packages/Package-restore-troubleshooting#this-project-references-nuget-packages-that-are-missing-on-this-computer