Visual Studio 2013 IntelliSense stops working for ASP.NET MVC5 Controllers

Question

I am facing a weird problem in my Visual Studio 2013 ASP.NET MVC 5 project. All of a sudden, the IntelliSense in the Controller classes of the MVC 5 project are not working

Answer 1

Close Visual Studio. Delete the .v12.suo file. Reopen solution.