I have two files that I managed to restore from a Firefox installation under Windows XP. The first one is urlclassifier3.sqlite and the second one is urlclassifier.pset
You can also replace the places.sqlite
file in the Firefox profile folder, and then, since the database may not be retrieved by Firefox, you can open another web browser (Chrome, Edge, etc.) and import your Firefox bookmarks from this new browser (most of the browsers can import Firefox bookmarks). Finally, from Firefox you can import the bookmarks again from this third-party web browser.