ok, now I understand what has happened. you will need ftp access to the server to be able to fix this.
you need to go to your server root.
now, you will need a copy of phpbb 3.0.11 get it here:
https://download.phpbb.com/pub/release/ ... 3.0.11.zip
download that to your computer, unzip it.
now using ftp if you know how to use it or your bluehost control panel file manager if not, you will need to upload the file named index.php to the root of your server. That is where you will see a file named config.php ( since wordpress is also installed in the root you may have other files with similar names but not exactly. there is already a file there named index.php but that is for wordpress and we need to replace it with the one from the phpbb 3.0.11 download.
that should get your board back.
there is no official support here for a version that old so if you need help just send me a PM or email and I will help you get this solved.