I have lot of documents which start with 3 lines of user headings. None of them are showing now. However MS Word can rescue them! What is happening?

These documents use headings created by me and based on Heading 1 or 2 and 5. I have had no problem with this until this year. Tried to upgrade to 5.4 today with the same result.
The odd thing is that M$ Word can rescue the filew (from being corrupt!) and then everything shows but all formats chance.

Is there something I can do to retrieve theses files?

I seem to have found the solution to this problem: It is the new “feature” of the LO-team (which seem to have lost ground!) to say goodbye to all fonts not in OpenType in favor of some improvement in speed! NO OPTION!!!

This means I have to change almost every LO Writer document (and maybe others!) I have ever made. HEY GUYS, START THINKING: The Past Will Never Leave You! Please give us the option again of keeping our old documents intact!!!

With not so many thanks this time (since you are behaving like the Enemy, M$oft, which the FSF has always fought against owing just to that),