Retain textbox values while Gridview Paging - asp.net

Question

On page index i am not able to hold the given value in the TextBox ,i have tried different logics but nothing is giving a correct result
here is Code
protected void gvViolationCodes_PageIndexChanging(object sender, GridViewPageEventArgs e)
{
RememberOldValues();
//to rebind the data based on changed page index
violationCodePresenter.GetViolationCodesList(Convert.ToInt32(ddlStatus.SelectedValue), Convert.ToInt32(Session["LanguageID"]));
gvViolationCodes.PageIndex = e.NewPageIndex;
gvViolationCodes.DataBind();
RePopulateValues();
}
and the Method to store previous values is as follows
private void RememberOldValues()
{
DataTable dt = new DataTable();
dt.Columns.Add("row_index");
dt.Columns.Add("edited_value");
foreach (GridViewRow gvr in gvViolationCodes.Rows)
{
TextBox tb = (TextBox)gvr.FindControl("txtSeqNo");
HiddenField hf = (HiddenField)gvr.FindControl("HiddenField1");
if (tb.Text != hf.Value)
{
DataRow dr = dt.NewRow();
dr["row_index"] = gvr.RowIndex;
dr["edited_value"] = tb.Text;
dt.Rows.Add(dr);
}
}
if (dt.Rows.Count == 0 && Session["retain"] == null && Session["page-index"] == null)
{
Session["retain"] = null;
Session["page-index"] = null;
}
else if (dt.Rows.Count > 0 && Session["retain"] == null && Session["page-index"] == null)
{
Session["retain"] = dt;
Session["page_index"] = gvViolationCodes.PageIndex;
}
else if (Session["retain"] == null && Session["page-index"] == null)
{
Session["retain"] = dt;
Session["page_index"] = gvViolationCodes.PageIndex;
}
}

Answer 1

Use ViewState object to hold textbox values across page postback which is occurring because of paging in gridview.