Improve my query or my database ( Statistics )

hello,
     I see a query in my statspack report because this query do plenty of access disk : 2,771,398
and for it i would retrieve my full query by the old_hash_value.
and when I execute  next query the query do not find a result no rows.
how can i do to retrieve this query full for execute an explain after and maybe improve my query or my database tunning ?

best regards
JP
 
select sql_text from v$sqltext where hash_value = '&hash_value_of_sql'
order by piece;

no rows


                                                                                   CPU      Elapsd   Old
  Buffer Gets    Executions  Gets per Exec  %Total Time (s)  Time (s) Hash Value