How to change the index of previous selected Dropdownlist?
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I have gridview with template field of dropdownlist in each row.when i select any value from dropdownlist it will change color of 3rd row below than it.But when i click on another dropdownlist it is changing the color of 3rd row below than it but the index of previous dropdownlist is not changed to 0 i.e"Select".it is still showing the value selected in last dropdown list.I just want when i click on a dropdownlist ,all other dropdownlist should be indexed to 0 i.e "Select" except one which i have clicked.
I am doing following in Selectedindexchange event of dropdownlist:

    protected void GridView1_SelectedIndexChanged(object sender,EventArgs e)
        {
           
            foreach (GridViewRow gvRow in GridView1.Rows)
            {
                   int g1 = gvRow.RowIndex;
                   GridView1.Rows[g1].BackColor = Color.White;
             }
                DropDownList ddl = (DropDownList)sender;
                GridViewRow row = (GridViewRow)ddl.NamingContainer;
                int g = row.RowIndex + 3;
                int current_row_index = row.RowIndex;
                int pp = GridView1.Rows.Count;
                 GridView1.Rows[g].BackColor = Color.Red;
             }
         }

Thanks in advance.