Question

I have a button in GridView and i want to enable it only on the selected row and when i select a new row button should be invisible for previous row?

Answer 1

You could use GridView's SelectedIndexChanged event to loop all rows and find your buttons. If it’s the button in the SelectedRow show it, hide them otherwise:

protected void GridView1_SelectedIndexChanged(Object sender, EventArgs e)
{
    var grid = (GridView)sender;
    foreach (GridViewRow row in grid.Rows)
    {
        var btn = (Button)row.FindControl("Button1");
        // Compare this row with the currently selected row using the SelectedRow property
        // SelectedRow might be null, the logic would work anyway
        btn.Visible = row == grid.SelectedRow;
    }
}