This is now the official forum for the new MAGIX version of Sound Forge.
The Sony Creative Software Help Center currently still includes knowledgebase articles for their versions of Sound Forge at https://www.custcenter.com/app/answers/list/p/802,16 Most should still apply to MAGIX Sound Forge. [Edit: Sony have now removed the Sound Forge articles]
Unfortunately, you have made your first post here, asking about how you might access an older version of Sound Forge, in an old thread asking about where the Sound Forge forums etc. are to be found!
Clearly, those forums are right here, so please post your question to a new thread here! However, whether anyone will be able to help you I honestly don't know. Did you previously have SF12 or older? In which case, it should be possible for your to obtain it again, but if not, I suspect you may be unlucky, sorry.