1. Turn off the power and again on to start the device.
2. Now bring device into ROM monitor mode. It can be done by using BREAK key or sequence might be CTRL-BREAK or CTRL-D or another combination, it varies by system to system.
3. At the > prompt, type o (it’s not zero) to record the current value of configuration register (or it can be 0x2102 or 0x102).
4. Type o/r 0x2142 to tell the router to boot from Flash without loading configuration in NVRAM (Startup-Configuration) at the next reload.
5. Type i to have the router reboot, the router ignores the configuration in NVRAM.
6. Now the router run the setup dialog, type no or press Ctrl-C to skip the initial setup dialog.
7. Type enable at the line mode to enter into the privilege mode
Router > enable
8. Copy the startup-configuration to running-configuration by using command
Router# copy startup-configuration running-configuration
Note: Do not type configure terminal, if you did so you over write the configuration stored in NVRAM.
9. View the configuration by giving command given below.
Router# show running-configuration
View the configuration, Line password, vty and Enable Password while an encrypted password need to be changed.
10. Enter Configuration mode and change the enable, line and vty password.
Router# configure terminal
Router (config) #
11. No shutdown all the interfaces that you are using.
12. Type config-register 0x2102 to return router to normal operation at next reload.
13. Exit configuration by Ctrl-Z
Router (config) # press Ctrl-Z
14. Save your changes by command given below.
Router# copy running-configuration startup-configuration
15. Reload the router to verify the password.