How to Reset Cisco Router Password

The (>) prompt is for the ROM monitor mode. If you are having a problem interrupting the boot sequence of the router, you might be interested in this procedure to simulate break key sequence.
2. Now you should change the value of the configuration register in order to make the router neglect the contents of the NVRAM in the next boot up. This is achieved using the following command:
> o/r 0x2142
This command will change the sixth bit (originally the configuration register is 0x2102) to one. By doing so, the router will act as new in the next boot, i.e., the router will not look for the startup-config in the NVRAM.
3. Perform a restart to the router using the following command:
> i
The (i) stands for (initialize).
4. The router now will restart and ask you if you want to use the setup mode and of course you will say no. Now, in order not to loose the configuration that you already have in the router, you should go to the USER privileged mode and perform:
Router#copy start run
This will get you back your old configuration but with one exception, you already are in the privileged mode without having to know the password..!!!!
Now you put a new password or passwords if you may:
Router(config)#enable secret whateveryouwnt
And you can also put new console and telnet passwords if you like.
5. To get things going back to normal, change the value of the configuration register to its original form (0x2102) using the following global configuration command:
Router(config)#config-register 0x2102
6. Now you should save the configuration including the new passwords that you know:
Router#copy run start
7. Now reload and you are good to go:
Router#reload