Order by in Session DataTable using linq / or some other method

hi i need to bind the gird values from session datatable(using order by)

thanks in advance..

public void ItemsToGrid()
    {
        if (Session["ItemsToGrid"] == null)
        {
            DataTable dt = new DataTable("ItemsToGrid");
            dt.Columns.Add(new DataColumn("ItemID", typeof(string)));
            dt.Columns.Add(new DataColumn("ItemName", typeof(string)));
            dt.Columns.Add(new DataColumn("UOM", typeof(string)));
            dt.Columns.Add(new DataColumn("Quantity", typeof(int)));
 
            Session["ItemsToGrid"] = dt;
        }
    }
in button click event am adding the rows into the Session datatable
 
try
        {
            string itemname;
            string itemid;
            if (this.ddltype.SelectedIndex == 0)
            {
                itemname = asbProduct.Text.ToString();
                itemid = asbProduct.SelectedValue.ToString();
            }
            else
            {
                itemname = txtItemName.Text;
                itemid = "0";
            }
 
            string UOM = txtUOM.Text;
            int quantity = Convert.ToInt32(txtquantity.Text.ToString().Trim());
 
            DataTable dt = new DataTable("ItemTable");
            dt = (DataTable)Session["ItemsToGrid"];
 
            DataRow dr;
            dr = dt.NewRow();
            dr["ItemID"] = itemid;
            dr["ItemName"] = itemname;
            dr["UOM"] = UOM;
            dr["Quantity"] = quantity;
            dt.Rows.Add(dr);
 
            // Here i need to do the group by with the datatable 
            Session["ItemsToGrid"] = dt;        
            AddGridItems();
}

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