Why deploying and then running asmx service throws 500 error?

I have a webservice in asmx. I am hosting it to the IIS 7.0 in the Default Web Site but it throws an error upon browsing.

HTTP Error 500.19 with this code 0x80070021

Also, upon expanding the folder in IIS it doesn't show web.config and .asmxfile even it's there right in the folder.

Folder internal view:

Webservice Code:

namespace Plant_WebService
{
    /// <summary>
    /// Summary description for EngineeringData
    /// </summary>
    [WebService(Namespace = "http://tempuri.org/")]
    [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
    [System.ComponentModel.ToolboxItem(false)]
    // To allow this Web Service to be called from script, using ASP.NET AJAX, uncomment the following line. 
    // [System.Web.Script.Services.ScriptService]
    public class EngineeringData : System.Web.Services.WebService
    {

        [WebMethod]
        public string HelloWorld()
        {
            return "Hello World";
        }

        [WebMethod]
        public bool InsertEngineeringData(string FunctionalLocation, string EqptType, string WINFileNo, string ComponentTagNo)
        {
            bool Status = false;

            EngineeringDataDAL EngineeringDataDAL = new Vail_PlantWebApi.EngineeringDataDAL();

            Status = EngineeringDataDAL.InsertEngineeringData(FunctionalLocation, EqptType, WINFileNo, ComponentTagNo);

            return Status;
        }
    }
}