Were you trying to root the phone or were you flashing the ROM etc for some other purpose? The general suggestion to resolve this seems to be: restore the phone to factory defaults (wiping all the contents on the phone therein.) If you save your contents to a memory card slotted into the phone, then restoring the phone to factory defaults would be painless. The manual for your phone will tell you how to do the restore to factory defaults.
- - - - - - Any opinions expressed by myself are entirely my own and do not represent Virgin Media in any way.