need to get selected value from dropdownlist and textbox

You are  missing :-
cmd.Connection = con;

public void BindData()
    {


        SqlConnection con = new SqlConnection(connection);
        SqlCommand cmd = new SqlCommand();
        cmd.CommandText = "sam_proc_MyProcedure";
        cmd.CommandType = CommandType.StoredProcedure;
        cmd.Connection = con;
        cmd.Parameters.Add(new SqlParameter("@roll", SqlDbType.VarChar)).Value = ddlDropDown.SelectedValue;
        cmd.Parameters.Add(new SqlParameter("@Name", SqlDbType.VarChar)).Value = txtTextBox.Text;
        con.Open();        
        SqlDataAdapter da = new SqlDataAdapter(cmd);
        DataTable dt = new DataTable("TableName");
        da.Fill(dt);
        con.Close();
        gdvMyDetails.DataSource = dt;
        gdvMyDetails.DataBind();


    }

protected void butSubmit_Click(object sender, EventArgs e)
    {
        MyMethod(Convert.ToInt32(ddlSearching.SelectedValue.ToString()),    Convert.ToInt32(txtMySalary.Text.ToString()));
 }

public void MyMethod(int DropDownloaValue, int TextBoxValue)
    {        
        SqlConnection con = new SqlConnection("");
        SqlCommand cmd = new SqlCommand();
        cmd.CommandText = "sam_proc_MyProcedure";
        cmd.CommandType = CommandType.StoredProcedure;
        cmd.Connection = con;
        cmd.Parameters.AddWithValue("@Selection_Type", 1);
        cmd.Parameters.AddWithValue("@EmpType", DropDownloaValue);
        cmd.Parameters.AddWithValue("@Salary", TextBoxValue);
        SqlDataAdapter da = new SqlDataAdapter(cmd);
        DataSet ds = new DataSet("MyTable");
        da.Fill(ds, "MyTable");
        gdvDailyReports.DataSource = ds;
        gdvDailyReports.DataBind();
    }

Stored Procedure
--=========================================================    
-- CREATE BY  :    
-- CREATE DATE  : <--/--/---->    
-- MODIFY BY  :    
-- MODIFY DATE  : <--/--/---->    
-- DESCRIPTION  :    
--=========================================================    
CREATE PROCEDURE sam_proc_MyProcedure 
 @Selection_TypeINT=0,    
 @EmpTypeINT=0,
 @SalaryINT=0  
AS    
BEGIN    
 IF(@Selection_Type=1)    
  BEGIN    
   SELECT NAME, [ADDRESS] , MOBILE, PHONE FROM EmployeeMaster WHERE EmpType=@EmpType AND Salary <=@Salary
  END
   IF(@Selection_Type=2)    
  BEGIN    
   SELECT NAME, [ADDRESS] , MOBILE, PHONE FROM EmployeeMaster WHERE EmpType=@EmpType AND Salary >=@Salary
  END  
 END  
--========================================================= 


Hope Your Problem Will Solve, Otherwise send me reply or Show me Your codding,
I'll try to solve your problem

hiii

It will better to read about sp_executesql and make query and use it .

thanks