1-We tried last month to backup our Oracle Express database files (the ones contained in /XE) by copying them to another directory.
2-Last week we needed those files because of a bad query that erased us some data.
3-We intended to restore database just by overwriting that current *.dbf files with the ones in our backup.
4-Since then, Oracle refuses to start or open connections. (We tried with Oracle SQL developer, the web management console host:8080/apex, etc) with the same results.
We know the data is still intact and there's no corruption cause through the DBViewer tool (intended to take out money for recovery) we were able to test our *.dbf files.
I also want to mention that I DON'T know
A-What's a Control File
B-What's a Password File
C-What's a Parameter File
D-Where is the Data Pump tool located and how does it works
E-How to read the init.ora file in order to correct the problem
At last, I should mention that I have a complete backup of all the Oracle express directory (Flash Recovery Area, Data and all included) and I'm not able to restore my database from that "physical structure" by overwriting a working Oracle copy (cause int that case I just mess up all my Oracle).
My questions
1-How can I (step by step for dummies) restore tables, schemas, users, privileges from my Oracle files (*.dbf and the other ones) in a fresh Oracle installation.
2-If it's possible to restore my production database just by "editing some config files" just they correctly point into my dbf's.
3-Why the Oracle instance appears to be running but it refuses connections when I overwrite the *.dbf files.
4-How can I possibly use some mentioned tools as Data Dump, DUL, WHERE TO FIND THEM.
5-Any other possible solutions or further guidance will be really helpful.
An easy to use & GUI option DUL is PRM-DUL:DBRECOVER for Oracle
DBRECOVER Recovery Options
For Oracle incidents, start with the DBRECOVER for Oracle trial to verify table visibility, row previews, and export readiness on copied datafiles. For MySQL and InnoDB incidents, DBRECOVER for MySQL is free software and can inspect.ibd files, ibdata1, and database directories locally.
When the case is urgent, preserve the original files first, work from copies, and contact paid emergency support with the database version, platform, error messages, file list, and recovery objective.