I'm running version 5.7.1 and was quite happy with that. But now I can only access the most recent import of photos. All previous photos are out of reach, as the sub-menue point "Show all" is not active. Any help as to re-gain acces, is much appriciated. Thank you. I run on Mac OS 10.13.6.
However, the reset-dialogue I get, when I follow the advise of The Lightroom Queen, is quite different the one shown on the link you so kindly proviede. I will look into this path, once I can do it in a calm and orderly fashinon. I don't like the idea of getting it wrong.