Hi @Antonios Kokiantonis ,
Welcome to Microsoft Q&A!
Which version of Visual Studio are you using?
Do you mean that you can’t find the “Manage NuGet Packages…” like this?
Please open the Visual Studio Installer > Modify > Individual components > search “NuGet package manager” > ensure that it is installed. If it has been installed, you can try to uncheck the component and reinstall it.
Besides, please check that you open a project with the solution file in the Solution Explorer.
Sincerely,
Anna
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