Oracle:sys, System failed to log on: Ora-01031:insufficient privileges__oracle

Please enter user name: Sys/sys as Sysdba
ERROR:
Ora-01031:insufficient Privileges

Please enter user name: System/system as Sysoper
ERROR:
Ora-01031:insufficient Privileges

SYS, the system user is unable to log on and shows no permissions:

Sql> Conn System/system
is connected.
sql> Grant SYSDBA to Sys
2;
Grant SYSDBA to Sys
*
ERROR is on line 1th:
ORA-01031: Insufficient Permissions

The password file was recreated, or not.

View User:

Sql> Conn System/system
is connected.
Sql> select * from V$pwfile_users;

No rows selected

Finally check the Sqlnet.ora file under D:/oracle/ora92/network/admin and find that the file does not exist.

After copying a file, you can log on normally:

Sql> Conn/as SYSDBA
is connected.
Sql>