If you had them working why not simply use the voices folder from a working backup of yours?
Otherwise you might have to do some manual editing of the files.
Some releases have the same numbers as others or the uploader used different numbers to match a collection - usually the meta codes for those voices are posted together with download, requiring the use of a custom meta.txt.
If you don't have a matching name and number for a voice inside the meta.txt than a voice can't be activated.