Unable to login after Phishing attack

Using an older version of WordPress our site was taken over by pishers who used the WordPress and phpbb directories to run their banking scams. We kept getting reinfected, and several different people were involved blocking the attack.

No one can log on now, even with new passwords. Perhaps a ligit file to two were deleted in error. This may cause a problem updateing as well. I am thinking that I may be forced to delete all files and directories and reinstall the newest version fresh. The origional package was provided by the sites host.

Comments Please, Thanks