if you want to find perticular Control inside the GrideView for below sample Example explains :-
Whether CheckBox in 5Th row of the gridview is checked or not
foreach(GridViewRow gvRow in gdv.Rows)
{
CheckBox chk = (CheckBox)gdv.Rows[gvRow.RowIndex].FindControl("chkItem");
if(chk.Checked)
{
// write your own logic....
}
}