Hello,
You haven't explained how and why you got into this situation.
Now where you are now is that your DB requires recovery. I do hope this is just your little play system and not a production.
So from where you are right now.
1. connect / as sysdba ;
2. shutdown immediate ;
3. startup mount ;
4. recover database until cancel ;
5. alter database open [noresetlogs or resetlogs] ;
You *must* have all the redo logs needed for a complete recovery to hand.
Please take your time and go through the steps one by one and not rush through.
Kindest Regards,
Amerjit