how to return json data from web api

Open WebApiConfig.cs file in solution and add mentioned line in it as shown in example.

var formatters = GlobalConfiguration.Configuration.Formatters;

formatters.Remove(formatters.XmlFormatter);

Or
 config.Formatters.Remove(config.Formatters.XmlFormatter);

Or

public static void Register(HttpConfiguration config)

{

config.Routes.MapHttpRoute(

name: "DefaultApi",

routeTemplate: "api/{controller}/{id}",

defaults: new { id = RouteParameter.Optional }

);

//To produce JSON format add this line of code

config.Formatters.JsonFormatter.SupportedMediaTypes.Add(newMediaTypeHeaderValue("text/html"));

}