Some time ago many file attachments were deleted by the administrator (Roger Brenizer), as far as I know to free up some space on the forum server, which was "brimming" at the time. Affected users can re-upload the affected attachments at any time (as long as the file types are permitted here as attachments).
In the case of these Organ Voice Set files, however, this is not necessary in my opinion. With these files (e.g. .vce, .org, etc.) you don't get any new voices, as mentioned, but only other settings of preset voices (which you can relatively easily make yourself). There are also plenty of organ voice files available on the psrtutorial.com site I linked above. (Search in the collections e.g. for "B3", "hammond" or "organ".)
Best regards,
Chris