Search according to date and time

private void Search()
{
// Get start date and end date of Current Week//
DayOfWeek day = DateTime.Now.DayOfWeek;
int days = day - DayOfWeek.Monday;
DateTime startD = DateTime.Now.AddDays(-days);
DateTime endD = startD.AddDays(6);

// Get start date and end date of Current month //
DateTime startM = new DateTime(DateTime.Now.Year, DateTime.Now.Month, 1);
DateTime endM = startM.AddMonths(1).AddDays(-1);


DateTime? OrderDate = null, StartOrderDate = null, EndOrderDate = null;


ViewState["sContent"] = null;
//string Title = txtTitle.Text;
if (ddlPeriod.SelectedItem.Value != "Select")
{
if (ddlPeriod.SelectedValue == "Today")
OrderDate = Convert.ToDateTime(DateTime.Now.ToShortDateString());
else if (ddlPeriod.SelectedValue == "Yesterday")
OrderDate = Convert.ToDateTime(DateTime.Now.AddDays(-1).ToShortDateString());
else if (ddlPeriod.SelectedValue == "This Week")
{
StartOrderDate = startD;
EndOrderDate = endD;
}
else if (ddlPeriod.SelectedValue == "This Month")
{
StartOrderDate = startM;
EndOrderDate = endM;
}
else if (ddlPeriod.SelectedValue == "Date Range")
{

if (!string.IsNullOrEmpty(txtDateRange1.Text))
StartOrderDate = Convert.ToDateTime(txtDateRange1.Text);
if (!string.IsNullOrEmpty(txtdaterange2.Text))
EndOrderDate = Convert.ToDateTime(txtdaterange2.Text);
}
}
//int CatId = 0;
//if (Request.QueryString["CategoryID"] != null)
// CatId = Convert.ToInt32(Request.QueryString["CategoryID"]);
//if (Title != null)
// Title = Title.Replace("'", "''");
int onumber = 0;
if (!string.IsNullOrWhiteSpace(txtorderno.Text))
onumber=Convert.ToInt32(txtorderno.Text);

GetOrders(onumber, txtcustname.Text, txtemail.Text, OrderDate.ToString(), StartOrderDate.ToString(), EndOrderDate.ToString(), chkDisable.Checked);
//GetOrders((Convert.ToInt32(txtorderno.Text)));
}