thank you friends , for suggesting me ..
i solved my self
i retrived last second row by taking count-2;
here is the code :
cmdd = new OleDbCommand("select * from logindetails where [lusername]='" + loginusername + "'", conn);
conn.Open();
cmdd.ExecuteNonQuery();
OleDbDataAdapter da = new OleDbDataAdapter(cmdd);
da.Fill(dt);
da.Fill(ds);
int i;
for ( i = 0; i <= dt.Rows.Count-2;i++ )
{
lbllogin.Content = dt.Rows[i]["login"].ToString();
lbllogout.Content = dt.Rows[i]["logout"].ToString();
}
conn.Close();
:)