Recompile the method of an invalid object in PLSQL or the specified object

Oracle Tips, Tricks & Scripts
1. Topic: Compiling Invalid Objects:

Oracle8i and Oracle9i provides a script called utlrp.sql located in $ORACLE_HOME/rdbms/admin which can be used anytime to recompile all exisiting PL/SQL modules (procedure, functions,packages,triggers, types, and views) in a database.

Invalid object:
$ORACLE_HOME/rdbms/admin/utlrp.sql
or
Compile the specified object:
Process:
alter procedure procedure_name compile;
Function:
alter function function_name compile;
Package:
alter package package_name compile;
Inclusions:
alter package package_name compile body;