Debian Buseter 10 Broken libreoffice
 

I ran Synaptic Package Manager a couple days ago, and it applied a whole load of updates and since then I have no LibreOffice.

If I go to search for LibreOffice and click the box to mark for installation the box turns red in colour and in Properties it says status "Broken"

If I go into the Repositaries menu option of SPM I initiall get a message
"an error occurred"
E: Unable to correct problems, you have held broken packages.
E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.
E: Unable to correct dependencies
E: Cannot read vendors.list file.

NB I did change some time back the Distribution to "buster-backports" to get an update kernel. Could this be affecting things?

This will not fix things per se, but may suggest you what to do next. Open a terminal window and run dpkg -C

so problem was due to replacing buster with buster-backports in the list of repos. Should have been added. Once corrected and updated could install libreoffice.