You need to locate and run the file
If you are running your database in Linux, find the apxchpwd.sql file by
$ locate apxchpwd.sql
Then go to that directory and run SQLPlus.
Follow these instructions to recover your ADMIN password. Note this is not for reseting your workspace ADMIN account password. Its for resetting the password for ADMIN account for your entire APEX installation. Open command prompt and cd to
Run sqlplus from command prompt.
Run the command alter session set current_schema=’apex_040000′; Run the command @apxchpwd.sql and enter your password.
You should now be able to log into http://localhost:8080/apex/apex_admin. APEX will ask you change your password again after logging in.