If the database is from a clean shutdown and no restore has been

  performed then it may be just the Online logs have been over-written.

  A useful quick check is:

     select * from v$recover_file;

  If this shows no rows then the following steps may be useful:

    a. If you do not know why the current online log is an old copy

       take a backup of all existing datafiles (V$datafile),

       controlfile (v$controlfile) and the online logs (even though old)

       (v$logfile). This ensures you can never get into a worse position

       than you are in now.

    b. Once you have a safe backup copy:

         startup mount

         recover database until cancel;

         ## This should report "Media recovery complete."

         alter database open resetlogs;

        如果报ora-01113 ora-01110使用_allow_resetlogs_corruption隐含参数

    c. Now shutdown take a FULL backup of all datafiles / logfiles and

       controlfile as you cannot perform recoveries through a resetlogs.