sorry to hear that
prefs.js (which contains them) is AFAIK one files backed up by ProfileBackup extension.
That is on alain's page. Best set the backup folder outside Profiles folder. It does not retsore files but keeps save back ups that can replace broken files.
p.s. Normally it is sufficient to have a save copy of K-Meleons's registry.dat to get all restored. That is the file that typically breaks when the OS crashes. Maybe have another close look after a second older XXXXXXXX.slt in application data/K-Meleon/default/... Broken registry.dat is much more common then the total loss of files. Maybe use windows search (prefs.js or bookmarks.html are the best candidates to search ). It might be worth Your effort.