The listener.ora file is just a text file. You can open it with Notepad and change the IP address. This is Personal Oracle right? The following is what my Listener.ora file looks like:

LISTENER =
  (ADDRESS_LIST =
        (ADDRESS = 
          (PROTOCOL = TCP)
          (Host = Mark)
          (Port = 1521)
        )
        (ADDRESS = 
          (PROTOCOL = TCP)
          (Host = 127.0.0.1)
          (Port = 1521)
        )
#        (ADDRESS = 
#          (PROTOCOL = SPX)
#          (Service = Mark_lsnr)
#        )
  )
STARTUP_WAIT_TIME_LISTENER = 0
CONNECT_TIMEOUT_LISTENER = 10
TRACE_LEVEL_LISTENER = ADMIN
SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (GLOBAL_DBNAME = Mark)
      (SID_NAME = ORCL)
    )
    (SID_DESC =
      (SID_NAME = extproc)
      (PROGRAM=extproc)
    )
  )

The generic IP address 127.0.0.1 just points to the local machine that Oracle is installed on even though I have a real IP addressed assigned to my computer.

>Dear all,
>I couldn't connect to my oracle 8.0.5 server after I changed the IP address from 172.16.x.x to 172.18.x.x. I have to change all my computers in my domain to 172.18.x.x. Everything is working properly after address change, except I couldn't connect to Oracle. I can ping to the server but I couldn't tnsping to it. There is error message in listener.log:
>
>(c) Copyright 1997 Oracle Corporation. All rights reserved.
>
>System parameter file is C:\orant\NET80\admin\listener.ora
>Log messages written to C:\orant\NET80\log\listener.log
>
>Listening on: (ADDRESS=(PROTOCOL=ipc)(PIPENAME=\\.\pipe\oracle.worldipc))
>Listening on: (ADDRESS=(PROTOCOL=ipc)(PIPENAME=\\.\pipe\EXTPROC0ipc))
>Listening on: (ADDRESS=(PROTOCOL=nmp)(PIPENAME=\\ORCSDA\pipe\ORAPIPE))
>Attempted to listen on: (DESCRIPTION=(CONNECT_TIMEOUT=10)(ADDRESS=(PROTOCOL=TCP)(HOST=orcsda)(PORT=1521)))
>TNS-12560: TNS:protocol adapter error
> TNS-00530: Protocol adapter error
> 32-bit Windows Error: 50: Unknown system error
>
>
>Question: How to fix this problem? What is the proper step of changing address for Oracle server?
>
>Now the listener service dies without giving any clue in the NT's event viewer. I can start it up, but after a few minutes the service will die.
>
>Thanks in advance,
>
>Gunawan Santoso