This is quite a complicated topic and you might have better luck on a specialized forum. See eg.
https://forums.oracle.com/forums/thread.jspa?threadID=921669.
If you highly value your database,
you should try to obtain professional help (eg. Oracle support - you can obtain it even if you didn't have a support contract beforehand, though the rates are rather steep; assuming your licences are all right). Trying to recover your database by your own means might make your situation worse still and render your data unrecoverable (assuming they can still be recovered).
If you can afford to lose your data (eg. it is a
test database and you can obtain a new copy from production), recreating it might be the easiest way to do it.