I deleted my wordbook directory contents How can I download the standard.dic or/and others
In the installation directory? Repair the installation.
In your user profile? You can restore them from <install_dir>/share/wordbook/
Your personal dictionaries can be restored from your backups (if you happen to run backups).
Thank you.
On arch linux, I find a dic file in /usr/share/hunspell. that has 80,000 words and is used by the application for basic spell check in English.
All in my user directory ~/.config/libreoffice/4/user/wordbook have been lost but creating a custom file adding custom words is a fairly trivial task.