I’m pretty sure any CCNA worth his salt has this procedure down pat, but here’s a summary with things to remember if you’re too lazy to plow through Cisco.
1. Reboot the router, have your console terminal all connected and ready.
2. Send break signal to the router before the POST – on Teraterm this means Alt-B or click on Control then Send break
3. Alter the configuration register value to ignore NVRAM contents.
4. Reboot the router again, so that you can boot into the router without a need for password.
5. Don’t get this command wrong after you enter privilege exec:
copy start run
Doing the reverse means a dump of an empty config onto your router. We are trying to edit the startup configuration, not overwrite the startup with the running (which is empty!).
6. Change the console and secret, change the configuration register back to default value.
line con 0
enable secret NEWSECRET
Don’t forget to write your new passwords down.
7. Save the configuration.
copy run start
8. Reboot the router, and enjoy.