Firefox automatically creates backups of your bookmarks. Did you turn this off?

Thanks..................all back now.

For future reference, see :

https://www.askvg.com/tip-enable-automatic-backup-of-mozilla-firefox-bookmarks-in-html-file-at-shutdown/

And also :

https://www.lifewire.com/how-to-backup-firefox-bookmarks-4587271

Note that if you notice you lost bookmarks or accidentally deleted bookmark(s) and you haven't closed Firefox yet then try "Organize > Undo" in the bookmarks manager (Bookmarks -> Show All Bookmarks) to undo this action and restore bookmark(s) you deleted accidentally or otherwise lost/misplaced. You may have to use Undo more than once (Firefox keeps a full undo history for the current session).

Thanks a million. All sorted !!

Glad to help. Safe Surfing.

Back up and restore information in Firefox profiles.{web link} I use an add-on that makes backups of my user profile, Just In Case. Unfortunately, it is not compatible with the current Firefox.

Every now and then, open the profile folder and create a copy of the current profile as is to another location on your hard drive. This way you will have a backup.

If you do this each day, you will not lose much data. This should be done with Firefox Closed.

Note: In case you need to restore from these backups, you may need to overwrite old or corrupted files.