You can find them listed on the following page but please take note of the big notice:
Linked below are the Subversion repositories for all of the retired bbPress 1.1 plugins. We’re committed to keeping them hosted here in perpetuity, though they should be considered retired and no longer active. http://bbpress.org/plugins/legacy/
Is it the shortcodes you are looking for? http://codex.bbpress.org/shortcodes/
Have a read of the docs on theme compatability to get your current theme working with bbPress
http://codex.bbpress.org/theme-compatibility/
As this site is bbPress you should probably post this the BuddyPress forums http://buddypress.org
This is fixed and will be in the next release of bbPress
(http://bbpress.trac.wordpress.org/ticket/2138)
From that error it appears and is actually the case that not all of the files for bbPress were updated on your web host when you updated bbPress.
- Make a backup of your site and database
- Open your WordPress Admin Dashboard and go to Plugins
- Deactivate the bbPress plugin (It should already be deactivated)
- Delete the bbPress plugin and accept the confirmation that it will delete those files
- Download the bbPress plugin again from the ‘Add New’ plugins section
- Activate the bbPress plugin
You should be all good to go now presuming this time your web host has downloaded and extracted all the files correctly to your site.
ps. If you ever do need to download a current or previous version you can download them in .zip form to manually extract and upload via FTP to your web host via http://wordpress.org/extend/plugins/bbpress/developers/
(The current version of bbPress at the time of writing is bbPress 2.2.3)
Via the docs FAQ http://codex.bbpress.org/faq/
Plugin Conflicts
To try and resolve conflicts with other plugins please disable all your plugins except bbPress to see if the error persists. Re-enable each plugin one at a time and if things break again you should be able to now know which other plugin is causing the conflict.
It looks like you have removed bbPress and installed Mingle Forums now
If you have downloaded a new WordPress theme that includes bbPress support you activate the theme from the WordPress Dashboard -> Appearance -> Themes ( /wp-admin/themes.php)
There are also some docs here on Getting Started with bbPress
Recover it from your backup or contact your web host to see if they have a backup
Ignore any issues with the bbpress.org /topics/feed/ as this is an isolated bug here on bbpress.org
You can test feeds with the W3C Feed Validator http://validator.w3.org/feed/
As to why your feed is failing I think is probably an issue with your web host as when I check your feed the results are “Server returned HTTP Error 404: Not Found” and I would expect IFTTT would also have problems parsing the feed.
http://validator.w3.org/feed/check.cgi?url=http%3A%2F%2Fprothemedesign.com%2Fforums%2Ffeed%2F
http://bbpress.org/topics/feed/ @ W3C Feed Validation Service
http://bbpress.org/forums/feed/ @ W3C Feed Validation Service
You maybe running out of either disk space or have limits on your database size.
Contact your web host support and ask them to check both of the above for you.
Are you running out of hard disk space or SQL database size with your web host?
That seems strange and we have had no other reports of an issue like yours.
Have you tried clearing your web browser cache or by posting from a different browser or computer?
I am not exactly sure what you are saying here!
Did you use the bbPress Import Tool to import your old phpBB forum into bbPress?
http://codex.bbpress.org/import-forums/
Ahmmm… OK… A couple of things to get started with…
I created a new page under Import Forums called Custom Import where we can start documenting how to go about actually customizing this file.
I also created a ticket #2134 as an update for Example.php is really needed to help improve the inline docs and code formatting to line up with the current bbPress1.php, phpBB.php and SimplePress5.php converters for improved readability will also help things along.
Now onto doing this… If we keep the discussion about Mingle here and update the codex as we go with any relevant information, steps and whatever else we bump into hopefully we will end up with some docs for customizing the included example importer.
I have the first few bits on the codex now, so go check that out 
ps. Anyone anyone can edit the codex docs pages using your bbpress.org credentials.
You can also use http://codex.bbpress.org/bbp_show_lead_topic/ as used here on bbpress.org to use a different template for the ‘lead topic’.
An alternative to your str_replace method is to make your own language translation. http://codex.buddypress.org/developer/extending-buddypress/customizing-labels-messages-and-urls/
