Moving this discussion to the Adobe Digital Editions forum.
What specific error message do you receive when you try to open your protected e-book in Bluefire reader?
Are these books that you bought or borrowed using you previous signon?
If so, you must use that signon to read them.
Do you still have a running version of Digital Editions that uses that old sign on?
If so, use the 'Library' dropdown 'Authorize Computer...';
it will tell you the username for the signon it is currently using.
If you have forgotten the password, you should be able to recover it using 'Trouble signing in?' on the signon page
Once you have these, you should be able to register Bluefire and read the books.