You should definitely backup your contacts/messages. Are you able to at least gain access via computer? From what I remember that phone didn't have an external memory stick so that may make recovery more difficult.

Some of the de-branding services have backup software but I *think* that assumes your phone can be accessed by your computer. From the description your giving I think one of the official service shops is your best bet. They may or may not be able to save the data that's on there. They almost certainly will be able to restore the firmware for you.

Sorry, not much hope there. :(