how to get dynamically create gridview control (textbox in rows) value and columns not fixed.

<asp:Button ID="btnHiddenPerson" runat="Server" Style="display: none" />
<ajaxToolKit:ModalPopupExtender ID="mpePerson" runat="server" BackgroundCssClass="modalBackground"
    TargetControlID="btnHiddenPerson" PopupControlID="Panel1" PopupDragHandleControlID="Panel2"
    Drag="True">
</ajaxToolKit:ModalPopupExtender>
<asp:Panel ID="Panel1" runat="server" CssClass="modalBox" Style="display: none;" BackColor="White"
    Width="500px">
            <asp:ImageButton ID="btnid" runat="server" Height="29px" ImageUrl="~/Image/close.jpg"
            onclientclick="window.close();" Width="27px" align="right" />
    <asp:Panel ID="Panel2" runat="server" CssClass="caption" Style="margin-bottom: 10px;
        cursor: hand;">
        Lot Information
        </asp:Panel>
    <asp:HiddenField ID="hidPersonEditIndex" runat="server" Value="-1" />
    <div class="divCol">
        Report Name</div>
    <div class="divColLast">
        <asp:DropDownList ID="ddlreportname" runat="server" OnSelectedIndexChanged="ddlreportname_OnSelectedIndexChanged" AutoCompleteType="FirstName"
        MaxLength="64" Width="180">
        </asp:DropDownList>
        <asp:ImageButton ID="ImageButton2" runat="server" Height="19px" ImageUrl="~/Image/refresh.jpg"
     Width="27px" onclick="Refreshpopup_Click" />
    </div>
    <div class="clearer">
    </div>
    <div class="divCol">
        Report Selection</div>
    <div class="divColLast">
        <asp:RadioButton ID="rbncompulsy" runat="server" Text="Compulsary" GroupName="RbnSelected"
            Enabled="false" />
        <asp:RadioButton ID="rbnoptional" runat="server" Text="Optional" GroupName="RbnSelected"
            Enabled="false" />
    </div>
    <div class="clearer">
    </div>
    <div class="divCol">
        Lot No</div>
    <div class="divColLast">
        <asp:TextBox ID="txtLotNo" runat="server" ReadOnly="true" AutoCompleteType="FirstName"
            MaxLength="64" Width="100"></asp:TextBox>
    </div>
    <div class="clearer">
    </div>
    <div style="width: auto; height: 300px; overflow: auto">
        <asp:GridView ID="GridView3" runat="server" CellPadding="4" ForeColor="#333333" GridLines="None"
            OnRowDataBound="GridView3_RowDataBound">

            <AlternatingRowStyle BackColor="White" ForeColor="#284775" />
            <EditRowStyle BackColor="#999999" />
            <HeaderStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White"></HeaderStyle>
            <PagerStyle BackColor="#284775" ForeColor="White" HorizontalAlign="Center" />
            <RowStyle BackColor="#F7F6F3" ForeColor="#333333" />
            <SelectedRowStyle BackColor="#E2DED6" Font-Bold="True" ForeColor="#333333" />
            <SortedAscendingCellStyle BackColor="#E9E7E2" />
            <SortedAscendingHeaderStyle BackColor="#506C8C" />
            <SortedDescendingCellStyle BackColor="#FFFDF8" />
            <SortedDescendingHeaderStyle BackColor="#6F8DAE" />
        </asp:GridView>
    </div>
    <div style="white-space: nowrap; text-align: center;">
        <asp:Button ID="btnSavePerson" runat="server" Text="Save" OnClick="SaveLinewise" CausesValidation="true" />
    </div>
</asp:Panel>

protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)
    {
        if (e.CommandName.Equals("Show"))
        {
            MtrRef_flag = true;
            int index = Convert.ToInt32(e.CommandArgument.ToString());
            DataSet ds = cmncls.GetProjReportName(ddlProjectName.SelectedItem.Text);                       
            ddlreportname.DataValueField = "SamId";
            ddlreportname.DataTextField = "RepID";
            ddlreportname.DataSource = ds;
            ddlreportname.DataBind();
  

            if (ds.Tables[0].Rows[0]["Compulsary"].ToString() == "True")
            {
                rbncompulsy.Checked = true;
                rbnoptional.Checked = false;
            }
            else
            {
                rbncompulsy.Checked = false;
                rbnoptional.Checked = true;
            }
            Label LotNo = (Label)GridView1.Rows[index].FindControl("LblLotNo");
            Label StartingNo = (Label)GridView1.Rows[index].FindControl("LblStartingNo");
            Label EndingNo = (Label)GridView1.Rows[index].FindControl("LblEndingNo");
            diffMeterNo = ((Convert.ToInt32(EndingNo.Text)) - (Convert.ToInt32(StartingNo.Text)));
            LowerVal = (Convert.ToInt32(StartingNo.Text));
            UpperVal = (Convert.ToInt32(EndingNo.Text));

            
            txtLotNo.Text = LotNo.Text;
            GridView3.DataSource = null;
            GridView3.DataBind();
            mpePerson.Show();
        }

    }
    protected void GridView3_RowDataBound(object sender, GridViewRowEventArgs e)
    {
        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            if (e.Row.RowIndex==0)
            {
                ddlMeterNo = new DropDownList();
                ddlMeterNo.ID = "ddlMeterNo";
                ddlMeterNo.Width = 60;
                e.Row.Cells[2].Controls.Add(ddlMeterNo);
                ddlMeterNo.Items.Clear();
                ddlMeterNo.Items.Add("Select Metere No");
                for (int range = LowerVal; range < UpperVal; range++)
                {
                    if (!list.Contains(range))
                        ddlMeterNo.Items.Add(range.ToString());
                }
            }
            if (e.Row.RowIndex > 0)
            {
                for (int i = 0; i < list.Count; i++)
                {
                 
                    TextBox txtMeterNo = new TextBox();
                    txtMeterNo.ID = "Meter" + (i + 1).ToString();
                    txtMeterNo.Width = 50;
                    e.Row.Cells[i + 2].Controls.Add(txtMeterNo);
                }
            }
        }
    }

    protected void SaveLinewise(object sender, EventArgs e)
    {
        string t="";
        TextBox m;
        try
        {
            for(int i=0;i<gridview3.rows[1].cells.count;i++)>
            {
            t = GridView3.Rows[1].Cells[i].Text.ToString();
            if (t.ToString() == " ")
            {
                m = (TextBox)GridView3.Rows[1].Cells[i].FindControl("Meter1");
                string o = m.Text.ToString(); 
            }
            }
        }
        catch (Exception ee)
        {

        }

         TextBox Txt = (TextBox)GridView3.Rows[2].Cells[2].FindControl("Meter1");

        cmncls.ShowMessage(Txt.Text, this);

     }
    protected void Refreshpopup_Click(object sender, ImageClickEventArgs e)
    {
        DataSet ds;
        DataTable dt1 = new DataTable();
        using (SqlConnection con = new SqlConnection(strConnString))
        {
            string strQuery = "SELECT ID,Parameter,Required FROM tbl_ParameterStandard where ProjCode = '" + ddlProjectName.SelectedItem.Text + "' And ReportName= '" + ddlreportname.SelectedItem.Text + "'";
            SqlCommand cmd = new SqlCommand(strQuery);
            using (SqlDataAdapter sda = new SqlDataAdapter())
            {
                cmd.Connection = con;
                con.Open();
                sda.SelectCommand = cmd;
                sda.Fill(dt1);
            }
        }

        ds = null;
        ds = cmncls.GetSampleSize(ddlProjectName.SelectedItem.Text);    //get samplesize                                                                                  
        String str = ds.Tables[0].Rows[0]["SampleSize"].ToString();
        int samplesize = Convert.ToInt16(str.ToString());

        if (MtrRef_flag == true)
        {
            list = new ArrayList();
            if (list.Count > 0)
                list.Clear();
            Random rdm = new Random();
            int num = 0;
            for (int i = 0; i < samplesize; i++)
            {
                num = Convert.ToInt32(rdm.NextDouble() * diffMeterNo) + (UpperVal - diffMeterNo + 1);
                if (list.Contains(num))
                    i--;
                else
                    list.Add(num);
            }
            MtrRef_flag = false;
        }
        DataTable dt = new DataTable();
        DataRow dr = null;
        dt.Columns.Add("Parameter");
        dt.Columns.Add("Required");
        dt.Columns.Add("MeterNo1");
        for (int i = 0; i < list.Count - 1; i++)
        {
            dt.Columns.Add("MeterNo " + (i + 2), typeof(string));
            dr = dt.NewRow();
        }
        dt.Rows.Add(dr);
        dr = dt.NewRow();

        dt.Rows[0]["Parameter"] = "";
        dt.Rows[0]["Required"] = "";
        for (int i = 0; i < list.Count - 1; i++)
        {
            dt.Rows[0]["MeterNo " + (i + 2)] = list[i].ToString();
        }
        dt.Rows.Add(dr);
        int inc = 0;
        int it = 1;
        dr = dt.NewRow();
        while (inc < dt1.Rows.Count)
        {
            dr = dt.NewRow();
            dt.Rows[it]["Parameter"] = dt1.Rows[inc][1].ToString();
            dt.Rows[it]["Required"] = dt1.Rows[inc][2].ToString();
            dt.Rows.Add(dr);
            it++;
            inc++;
        }
        ViewState["CurrentTable"] = dt;
        GridView3.DataSource = dt;
        GridView3.DataBind();
        mpePerson.Show();

    }