vertical ruler checked under view, does not appear
Your details just repeat the title and hence add no additional value/information.
Use `Help -> Restart in Safe Mode` and check whether the ruler appears while running in **Safe Mode** of LibreOffice (Don't miss to use button `Continue in Safe Mode`). If that works - reset your [LibreOffice user profile](https://wiki.documentfoundation.org/UserProfile) (also using `Help -> Restart in Safe Mode` and using the options to reset to factory settings).
And while you are at it: Please provide your operating system and LibreOffice version (info from Help -> About LibreOffice is essential for almost all answers to questions). Please use edit to add this information to the details of your question.