U may modify FEDORA_HOME/server/config/fedora.fcfg file and ensure that the datastore entry for Oracle points to the right host and database. The fedora.fcfg file that comes with the distribution uses a database on the local host called fedora20. When u start fedora, be sure to use the parameter “oracle”, as in fedora-start oracle.
While the server is running, it writes logs to FEDORA_HOME/server/logs. These are timestamped files, written in a simple XML format. It is best to use these logs to get more extensive information about what the server is doing or to diagnose problems.
As Carlosdl written the more details help to resolve ur Q properly. If possible supply the exact error with error no and see the Log file and note the what errors r there !