(1) First check "NLS_CHARACTERSET" of database through
SQL> select VALUE from nls_database_parameters where PARAMETER = 'NLS_CHARACTERSET';
(2) And then change language
HKEY_LOCAL_MACHINE/SOFTWARE/ORACLE/KEY_OraDb10g_home1/NLS_LANG
e.g: AMERICAN_AMERICA.WE8ISO8859P1
