my Login page cannot connect to Sqldatabase. Help modify code.

string constr = ConfigurationManager.ConnectionStrings["MyConnection"].ToString();
 
        SqlConnection conn = new SqlConnection(constr);
        SqlCommand cmd = new SqlCommand();
        cmd.Connection = conn;
 
SqlDataSource ads = new SqlDataSource();
 

  ads.SelectParameters.Add("UserName", this.TextBox1.Text);
  ads.SelectParameters.Add("Password", this.TextBox2.Text);
 
 ads.SelectCommand = "SELECT * FROM [Users] WHERE [UserName]= @UserName AND[Password] = @Password";
 
  //retrieve required data
   
 DataView dv = (DataView)ads.Select(DataSourceSelectArguments.Empty);
 
    //diplay error message if record is not found
     if (dv.Count == 0)
        {
 
   this.Label1.ForeColor = System.Drawing.Color.Red;
   this.Label1.Text = "Login failed. The username or password you have entered isn't valid";
            return;
        }
 
        //create Session variables
        this.Session["Username"] = dv[0].Row["Username"].ToString();
        this.Session["UserType"] = dv[0].Row["UserType"].ToString();
 
        //Redirect to respective page based on user 

             if (this.Session["UserType"].ToString().Equals("patient"))
                Response.Redirect("Patient.aspx");
 

            else if (this.Session["UserType"].ToString().Equals("doctors"))
            Response.Redirect("Doctor.aspx");
 

            else if (this.Session["UserType"].ToString().Equals("nurse"))
            Response.Redirect("Nurse.aspx");