How do I access a control within a static method?

[abcdef123ghi]

I need to show the message on a Datagridview,I tried the follwoing code,but it doesn't work

static void client_MqttMsgPublishReceived(object sender, MqttMsgPublishEventArgs e)
       {
        // handle message received 
        string message = System.Text.Encoding.UTF8.GetString(e.Message);

        string guildstr = Guid.NewGuid().ToString();
        string topicstr = "/lists/thenumber";
        string clientstr = "client";
        string usernostr = "userno";

        int index = myform.MsgDGView.Rows.Add();
        myform.MsgDGView.Rows[index].Cells[0].Value = "1"; // Exception occured
        myform.MsgDGView.Rows[index].Cells[1].Value = guildstr;
        myform.MsgDGView.Rows[index].Cells[2].Value = topicstr;
        myform.MsgDGView.Rows[index].Cells[3].Value = clientstr;
        myform.MsgDGView.Rows[index].Cells[4].Value = usernostr;
        myform.MsgDGView.Rows[index].Cells[5].Value = message;
        myform.MsgDGView.Rows[index].Cells[6].Value = DateTime.Now.ToString("yyyy-MM-dd hh:mm:ss");
        for (int i = 0; i < myform.MsgDGView.RowCount; i++)
        {
            myform.MsgDGView.Rows[index].Cells[0].Value = (i + 1).ToString();
        }

        myform.MsgTextBox.Text = message;
 }

[billbarni]

I don't know if it is related to the UI thread. Try this:

Invoke((Action)delegate
            {
                myform.MsgTextBox.Text = message;
            });