change text cell in datagrid (WPF)

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C#

WPF

hey
i need change cell text when i add a row in data grid

for add row i use this code

      public struct MyData
       {
                public int ID { set; get; }
                   public string name { set; get; }
                        public float cost { set; get; }
                        public float tedad { set; get; }
       }

            int i,j = 0;
DataGridTextColumn col1 = new DataGridTextColumn();
DataRow dr; DataTable dt;

dg2.Items.Add(new MyData() { ID = j, name = a[1], cost = Convert.ToInt64(b[1]) });
col1.Binding = new Binding("ID");
DataGridTextColumn col2 = new DataGridTextColumn();
col2.Binding = new Binding("name");
DataGridTextColumn col3 = new DataGridTextColumn();
col3.Binding = new Binding("cost");
 
DataGridTextColumn col4 = new DataGridTextColumn();
col4.Binding = new Binding("tedad");
if (i == 0)
{
    ++i;
    dg2.Columns.Add(col1);
    dg2.Columns.Add(col2);
    dg2.Columns.Add(col3);
    dg2.Columns.Add(col4);
}

now i want change name in cell name
when i use this code , i have a error
" Cannot modify the result of an unboxing conversion "

((MyData)dg2.Items[0]).name = "aref";

can you help me ?