All of my files have been converted to read only. I didnot do that. How can I change back to regular files?

Each time I open a file, it says it is read only. This happened after the most recent update to the software program and I did not do anything other than install the update.

Try to start LibreOffice in Safe Mode and open one (or more) files using File -> Open. If this doesn`t open your files read only, then most probably you user profile is corrupted and you should reset you user profile to factory settings.