ORA-28000: the account is locked
第一步：使用PL/SQL，登录名为system,数据库名称不变，选择类型的时候把Normal修改为Sysdba;
第二步：选择myjob,查看users;
第三步：选择system,右击点击“编辑”；
第四步：修改密码，把“帐户被锁住”的勾去掉；
第五步：点击“应用”再点击“关闭”；
第六步：重新登录就可以通过验证了；
第二种
ALTER USER username ACCOUNT UNLOCK;

第三种

在plsql developer中要是以scott/tiger登录时提示ora-28000 the account islocked。

解决办法：

新装完Oracle10g后，用scott/tiger测试，会出现以下错误提示：
       oracle10g the account is locked
       oracle10g the password has expired
原因：默认Oracle10g的scott不能登陆。
解决：
（1）conn sys/sys as sysdba; //以DBA的身份登录
（2）alter user scott account unlock;// 然后解锁
（3）conn scott/tiger //弹出一个修改密码的对话框，修改一下密码就可以了

在运行里面输入cmd在DOS模式下输入sqlplus，以system用户名登录，密码是刚装oracle时自己填写的密码orcl，登录进去以后。

SQL> conn sys/sys assysdba;      （分号是必须的但是我是以system登录的所在这不应该写conn sys/sys as sysdba应该写connsystem/orcl as sysdba;）
        Connected.
SQL> alter user scott account unlock;
        User altered.
SQL> commit;
        Commit complete.
SQL> conn scott/tiger//请输入新密码，并确认后OK
Password changed
Connected.

这时再到plsql developer里面以scott/tiger登录就可以了。。。。。

Oracle 10g 默认安装带来的用户名/密码
   Username
Password
Description
See Also

CTXSYS
CTXSYS
The Oracle Text account
Oracle Text Reference

DBSNMP
DBSNMP
The account used by the Management Agent component of OracleEnterprise Manager to monitor and manage the database
Oracle Enterprise Manager Grid Control Installation and BasicConfiguration

LBACSYS
LBACSYS
The Oracle Label Security administrator account
Oracle Label Security Administrator's Guide

MDDATA
MDDATA
The schema used by Oracle Spatial for storing Geocoder and routerdata
Oracle Spatial User's Guide and Reference

MDSYS
MDSYS
The Oracle Spatial and Oracle interMedia Locator administratoraccount
Oracle Spatial User's Guide and Reference

DMSYS
DMSYS
The Oracle Data Mining account.
Oracle Data Mining Administrator's Guide

Oracle Data Mining Concepts

OLAPSYS
MANAGER
The account used to create OLAP metadata structures. It owns theOLAP Catalog (CWMLite).
Oracle OLAP Application Developer's Guide

ORDPLUGINS
ORDPLUGINS
The Oracle interMedia user. Plug-ins supplied by Oracle and thirdparty format plug-ins are installed in this schema.
Oracle interMedia User's Guide

ORDSYS
ORDSYS
The Oracle interMedia administrator account
Oracle interMedia User's Guide

OUTLN
OUTLN
The account that supports plan stability. Plan stability enablesyou to maintain the same execution plans for the same SQLstatements. OUTLN acts as a role to centrally manage metadataassociated with stored outlines.
Oracle Database Performance Tuning Guide

SI_INFORMTN_SCHEMA
SI_INFORMTN_SCHEMA
The account that stores the information views for the SQL/MM StillImage Standard
Oracle interMedia User's Guide

SYS
CHANGE_ON_INSTALL
The account used to perform database administration tasks
Oracle Database Administrator's Guide

SYSMAN
CHANGE_ON_INSTALL
The account used to perform Oracle Enterprise Manager databaseadministration tasks. Note that SYS and SYSTEM can also performthese tasks.
Oracle Enterprise Manager Grid Control Installation and BasicConfiguration

SYSTEM
MANAGER
Another account used to perform database administration tasks