The 2500 series routers use a different cpu type and they are motorola, when you get rommon it is telling me that you have a risc based cpu and we are probably dealing with 2600 or 3600 series, it seems like you have lost your IOS, do you know how to load the IOS? if you do reload the IOS and it should be fine, 0x2142 or 0x2102 wont help you at all.
nabrik
Dual ccie 12410
narbik@earthlink.net