To reset some Cisco routers and switches, you need to enter ROMMON mode. To get into ROMMON, you can hold down the reset button on the front/back of the device for 5-10 seconds before IOS boots up. You also then need to press the BREAK key. If you don’t have a break key (you may be on laptop) you can send a break key through Putty, Click the menu > Special Command > Break Key. This should get you into Rommon mode. You need to type “confreg 0x142” and then reboot the router. This will cause the rooter to ignore the startup config. You can then boot into the router, do a “copy running-config startup-config” and reboot again. You next need to put confreg back otherwise the router will ignore the new settings you have overwritten. To do this, repeat the same process but set confreg to 0x102, reboot and your router/switch is fully reset.
|Configuration Register Setting