LibreOffice won’t start
Based on this detailed informations you will surely get a helpful answer.
Which OS do you have? Did you install LibreOffice or is it part of your OS distribution? What method are you trying to use to open LibreOffice, double click on document, shortcut on desktop etc. You could try re-install using latest version or uninstall and then install again. Also perhaps try to reset your LibreOffice user profile but we need to know your OS to describe the correct folders.
@mark_t: on most Linuxes, since they usually use a strict package management system, it won’t matter if the program is preinstalled since it’s always installed through the package system. That’s way different from older phones that predate a smartphone (for example my Nokia X3-00) and even then, where whatever is preinstalled stays the old way even if a new version is installed.
@rautamieka: I was just thinking if it was part of a Linux distribution and it isn’t starting then @Menno may not know what Version of LibreOffice he has installed. Now I realise I didn’t ask which version of LibreOffice he has, this would also be important to know.