Hi nauna,

Usng the below article i have created the example.

Return Identity value from Stored Procedure in SQL Server

Check this example. Now please take its reference and correct your code.

I have used Customers table. CustomerId is an Auto-Increment (Identity) column.

You can download the database table SQL by clicking the download link below.

Download SQL file

SQL

CREATE PROCEDURE [dbo].[AddCustomerReturnIDwithoutput] 
	@Name varchar(50),
	@Country varchar(50),
	@id int output
AS
BEGIN
	SET NOCOUNT ON;
	INSERT INTO Customers VALUES (@Name,@Country) 
	SET @id = SCOPE_IDENTITY()
	RETURN @id
END

DataAccess

using System;
using System.Collections.Generic;
using System.Web;
using System.Configuration;
using System.Data.SqlClient;
using System.Data;

public class DataAccess
{
    public DataAccess()
    {
    }

    public int InsertCustomer(string name, string country)
    {
        int id;
        string strConnString = ConfigurationManager.ConnectionStrings["conString"].ConnectionString;
        SqlConnection con = new SqlConnection(strConnString);
        SqlCommand cmd = new SqlCommand();
        cmd.CommandType = CommandType.StoredProcedure;
        cmd.CommandText = "AddCustomerReturnIDwithoutput";
        cmd.Parameters.Add("@Name", SqlDbType.VarChar).Value = name;
        cmd.Parameters.Add("@Country", SqlDbType.VarChar).Value = country;
        cmd.Parameters.Add("@id", SqlDbType.Int).Direction = ParameterDirection.Output;
        cmd.Connection = con;
        try
        {
            con.Open();
            cmd.ExecuteNonQuery();
            id = Convert.ToInt32(cmd.Parameters["@id"].Value);
        }
        catch (Exception ex)
        {
            throw ex;
        }
        finally
        {
            con.Close();
            con.Dispose();
        }

        return id;
    }
}

HTML

Name
<asp:TextBox ID="txtName" runat="server"></asp:TextBox>
<br />
Country
<asp:TextBox ID="txtCountry" runat="server"></asp:TextBox>
<br />
<asp:Button ID="btnInsert" runat="server" Text="Insert" OnClick="btnInsert_Click" />
<br />
<asp:Label ID="lblMessage" runat="server" Text=""></asp:Label>

C#

protected void btnInsert_Click(object sender, EventArgs e)
{
    DataAccess da = new DataAccess();
    int scopeId = da.InsertCustomer(txtName.Text.Trim(), txtCountry.Text.Trim());
    lblMessage.Text = "Record inserted successfully. ID = " + scopeId;
}

Screenshot