CHARACTER SET NLS

SQL> conn / as sysdba

select * from nls_database_parameters;

SHUTDOWN IMMEDIATE;

STARTUP RESTRICT;

ALTER SYSTEM SET JOB_QUEUE_PROCESSES=0;

ALTER SYSTEM SET AQ_TM_PROCESSES=0;

ALTER DATABASE CHARACTER SET AR8MSWIN1256;

If the above fails:

SQL>ALTER DATABASE CHARACTER SET INTERNAL_USE WE8MSWIN1252;

SQL>SHUTDOWN IMMEDIATE;

SQL>STARTUP;