try this...:)
protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow)
{
CheckBox chkBox= (CheckBox)e.Row.FindControl("chkbox1");
if(e.Row.Cells[2].ToString()=="no")
{
chkBox.Checked=false;
}
}
}