Follow these steps to recover your router.
Copy a new 2500 image to tftp from cco.
router(boot)# copy tftp flash
It might prompt a question copy flash with erase y/n?
After completion of the download
router(boot)# reload
_Note_ a question system configuration as been modified do you want to
save y/n ?
answer no.
If you pick yes you will overwrite you configs will be nvram with an empty config.