Issue in Character Set Change in Oracle Database 10g

@csalter

 At the time of changing the character set I am facing the issue.

SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup restrict
ORACLE instance started.

Total System Global Area 1077936128 bytes
Fixed Size                  2049464 bytes
Variable Size             427821640 bytes
Database Buffers          633339904 bytes
Redo Buffers               14725120 bytes
Database mounted.
Database opened.
@csalter.plb
SP2-0310: unable to open file "csalter.plb"
SQL> Disconnected from Oracle Database 10g Enterprise Edition Release 10.2.0.2.0 - 64bit Production
With the Partitioning, OLAP and Data Mining options
$ cd /erpapp/KMCBKP/db/tech_st/10.2.0/rdbms/admin/
$ sqlplus / as sysdba

SQL*Plus: Release 10.2.0.2.0 - Production on Thu Oct 29 13:11:35 2009