Here’s an updated solution I found as I had the same problem with Visual Studio 2015: ado.net model for db is gone Visual studio 2015
Paraphrasing: Change your installation of Visual Studio 2015 and include the Microsoft SQL Server Data Tools (via Control Panel > Program & Features > VS2015 > Change > Modify > Windows and Web Development > Microsoft SQL Server Data Tools).
After downloading the extension and restarting Visual Studio, you should be able to add ADO.NET Entity Data Model as a new item.
As I learned the hard way trying to follow older Visual Studio tutorials, trying to use View > Other Windows > Data Sources etc. doesn’t do the same thing.