Why Does My Router Lose Its Configuration

When your Cisco router finally boot up, enter to the privileged mode in order to execute a commands and check the current confreg value. 

When you type show version and press ENTER you will receive the configuration registry value. If the value is 0x2142 it means that the router bypasses the startup configuration stored in NVRAM during its boot sequence. 

In order to resolve that issue, you have to replace that value on configuration registry with the 0x2102. 

From the Router# prompt:

1.     Type configuration-terminal , and press ENTER.

2.     Type config-register 0x2102, and press ENTER.

3.     Type end, and press ENTER.

To verify the configuration register change, type show version at the Router# prompt, and review your show version command output again

When the router is reloaded, the new configuration register setting becomes active.

How to Perform a Factory Reset on a Cisco Router

Anyone who is interested to do a successful factory reset on a Cisco IOS needs to apply the below steps.

1) Power Off the Router.

2) Press and HOLD the reset button.

3) Turn the power back on.

4) Within a 60 Seconds Release the reset button and send the BREAK key/command from Console.

5) If you successfully do the above a rommon prompt on the screen.  

6)Type confreg 0x2142

7) Type reset and expect the router to restart. When the router comes back up you will be asked to start configure it. 

*** In order to enable Cisco to keep the new configurations you have to change the confreg again. ( Check Post Why does my router lose its configurations )