Basically I\'ve followed a tutorial and decided to delete the .mdf
file afterwards.
Now whenever I try to run the application I get the following error
I had the same error while following the tutorial on "Getting Started with ASP.NET MVC 5 | Microsoft Docs". I was on Visual Studio 2015. I opened View-> SQL Server Object Explorer and deleted the database named after the tutorial, then it could work. see Delete .mdf file from app_data causes exception cannot attach the file as database