To reset your Cisco 2600 router, just follow the instructions from this link.
If you forgot your router's password (enable password, enable secret, console) you need to reset your router through ROMmon.
To access the ROMmon mode, start your minicom and reboot your router. Upon booting send the CTR+BREAK sequence by pressing CTRL-A F on your keyboard.
System Bootstrap, Version 12.2(8r) [cmong 8r], RELEASE SOFTWARE (fc1)
Copyright (c) 2003 by cisco Systems, Inc.
C2600 platform with 98304 Kbytes of main memory
program load complete, entry point: 0x80008000, size: 0xacc0f0
Self decompressing the image : ########################
monitor: command "boot" aborted due to user interrupt
rommon 1 >
rommon 1 >
Then type this command to change the router's configuration register to 0x2142.
