help not downloaded at install how can I get the file?
If you are using one of the current releases, there are links to the offline help files on Download LibreOffice | LibreOffice - Free Office Suite - Based on OpenOffice - Compatible with Microsoft
For earlier versions start at Index of /libreoffice/old and select the appropriate version; note the help file version must match the version of LO you have installed.
If this answer helped you, please accept it by clicking the check mark to the left and, karma permitting, upvote it. That will help other people with the same question.
In case you need clarification, edit your question (not an answer) or comment the relevant answer.