You may need to do a password recovery to log back in. Once you gain access, then you can change the password. Below is a link that points to the steps for password recovery on a 1941 router.
Below are the detailed steps to perform a password recovery on a 1941 router.
Perform these steps in order to recover your password:
Attach a terminal or PC with terminal emulation to the console port of the router. Use these terminal settings:
9600 baud rate
No parity
8 data bits
1 stop bit
No flow control
Refer to these documents for information on how to cable and connect a terminal to the console port or the AUX port:
If you can access the router, type show version at the prompt, and record the configuration register setting. See Example of Password Recovery Procedure in order to view the output of a show version command.
Note: The configuration register is typically set to 0x2102 or 0x102. If you can no longer access the router (because of a lost login or TACACS password), you can safely assume that your configuration register is set to 0x2102.
Use the power switch in order to turn off the router, and then turn the router back on.
Note:
In order to simulate this step on a Cisco 6400, pull out and then plug in the Node Route Processor (NRP) or Node Switch Processor (NSP) card.
In order to simulate this step on a Cisco 6x00 with NI-2, pull out and then plug in the NI-2 card.
Press Break on the terminal keyboard a couple of times after you see the message program load complete, entry point: 0x80008000, size: 0x6fdb4c in order to put the router into ROMMON.
Note: The values of entry point and size are subjected to the routers.
If the break sequence does not work, refer to Standard Break Key Sequence Combinations During Password Recovery for other key combinations.
If unable to break into ROMMON mode, perform these steps:
Remove flash.
Reload the router. Router will end up in ROMMON mode.
Insert flash.
Perform standard procedure for password recovery.
Type confreg 0x2142 at the rommon 1> prompt in order to boot from Flash.
This step bypasses the startup configuration where the passwords are stored.
Type reset at the rommon 2> prompt.
The router reboots, but ignores the saved configuration.
Type no after each setup question, or press Ctrl-C in order to skip the initial setup procedure.
Type enable at the Router> prompt.
You are in enable mode and should see the Router# prompt.
Type configure memory or copy startup-config running-config in order to copy the nonvolatile RAM (NVRAM) into memory.
Warning: Do not enter copy running-config startup-config or write. These commands erase your startup configuration.Type show running-config.
The show running-config command shows the configuration of the router. In this configuration, the shutdown command appears under all interfaces, which indicates all interfaces are currently shut down. In addition, the passwords (enable password, enable secret, vty, console passwords) are in either an encrypted or unencrypted format. You can reuse unencrypted passwords. You must change encrypted passwords to a new password.
Type configure terminal.
The hostname(config)# prompt appears.
Type enable secret <password> in order to change the enable secret password. For example:
hostname(config)#enable secret ciscoIssue the no shutdown command on every interface that you use.
If you issue a show ip interface brief command, every interface that you want to use should display up up.
Type config-register <configuration_register_setting>. Where configuration_register_setting is either the value you recorded in step 2 or 0x2102. For example:
hostname(config)#config-register 0x2102Press Ctrl-z or end in order to leave the configuration mode.
The hostname# prompt appears.
Type write memory or copy running-config startup-config in order to commit the changes.
