Corrupted session again

It happened again: for 3 days now, every morning I launch Ardour (7) and try to start the session I was working on the day before, it cannot open it because of missing sources. I used to identify the missing source in the xml, delete it and after that it works, but of course without the aforementioned source. Today however, after the deletion it kept asking for a new unknown source, starting with the last track i had made, in the reverse order of recording, without end. Lost the whole session: 3 days of work. Bak files wouldn’t work either.