Flashback the procedure/package changes done at specific time by flashback feature in Oracle.
If we drop any procedure accidently then we recover from flashback.

In Example, we restore the dropped or changed procedure/package through flashback

1. Check the object id of the package/procedure/function.

SQL> select object_id from dba_objects where owner='HR' and object_name='FIND_DEPARTMENT_ID';
OBJECT_ID
----------
5024237

2. Retrieve the flashback code using timestamp.

SQL> select SOURCE from sys.source$ as of timestamp to_timestamp('23-Apr-2017 10:00:20','DD-Mon-YYYY hh24:MI:SS') where obj#=5024237;