The connection was not closed. The connection's current state is open.

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;
/// <summary>
/// Summary description for global
/// </summary>
public class global
{
    SqlConnection con = new SqlConnection("server=DHINESH\\SQLEXPRESS;database=password;integrated security=true");
    SqlCommand Com;
    SqlDataAdapter da = new SqlDataAdapter();
    DataSet ds = new DataSet();
    SqlDataReader dr;
    
	public global()
	{
        openCon();
	}
    ~global()
    {
        closeCon();
    }
    public void openCon()
    {
       string s = ConfigurationManager.ConnectionStrings["con"].ToString();
       this.con = new SqlConnection(s);
       this.con.Open();
       
    }
    public void closeCon()
    {
       
            
         // this.Con.Close();
        this.con.Close();
        
    }
        
    public int gettable(string[,] MyInparam, string MySpname)
    {
        this.Com = con.CreateCommand();
        this.Com.CommandText = MySpname.ToString();
        this.Com.CommandType = System.Data.CommandType.StoredProcedure;
        for (int i = 0; i < MyInparam.Length / 2; i++)
        {
            Com.Parameters.AddWithValue(MyInparam[i, 0], MyInparam[i, 1]);
        }
       int a= this.Com.ExecuteNonQuery();
       return a;
    }
    public int getvalue(string query)
    {
        this.Com=con.CreateCommand();
        this.Com.CommandText=query.ToString();
        this.Com.CommandType = CommandType.Text;
        int a = (int)Com.ExecuteScalar();
        return a;
    }
    public DataSet getdata(string query)
    {
        this.Com = con.CreateCommand();
        this.Com.CommandText = query.ToString();
        this.Com.CommandType = CommandType.Text;
        this.da = new SqlDataAdapter(Com);
        this.da.Fill(ds);
        return ds;
    }
    public DataSet getdataset(string[,] MyInparam, string MySpname)
    {
        ds = new DataSet();
        
        this.Com = con.CreateCommand();
        this.Com.CommandText = MySpname.ToString();
        this.Com.CommandType = System.Data.CommandType.StoredProcedure;
        for (int i = 0; i < MyInparam.Length / 2; i++)
        {
            Com.Parameters.AddWithValue(MyInparam[i, 0], MyInparam[i, 1]);
        }
        this.da = new SqlDataAdapter(Com);
        this.da.Fill(ds);
        return ds;
        
    }
    public string CreateRandomCode(int codeCount)
    {
        string allChar = "0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z";
        string[] allCharArray = allChar.Split(',');
        string randomCode = "";
        int temp = -1;
        Random rand = new Random();
        for (int i = 0; i < codeCount; i++)
        {
            if (temp != -1)
            {
                rand = new Random(i * temp * ((int)DateTime.Now.Ticks));
            }
            int t = rand.Next(36);
            if (temp != -1 && temp == t)
            {
                return CreateRandomCode(codeCount);
            }
            temp = t;
            randomCode += allCharArray[t];
        }
        return randomCode;
    }
}