Languages - How do I fix this "Installer unable to find language files" error I am getting

A critical error has occurred.

This installer was unable to find the installer's language file or files. They should be found under: /forum/Themes/default/languages

In some cases, FTP clients do not properly upload files with this many folders. Please double check to make sure you have uploaded all the files in the distribution. If that doesn't help, please make sure this install.php file is in the same place as the Themes folder.

Or

The languages directory has become corrupt during upload, try uploading it again. If it still doesn't work, try another FTP client, or another method.