Hello Grod,

Firefox backs-up your bookmarks every day, automatically.

Open the Library with control+shift+B. In the center near the top select Import and Backup. Hover your cursor over Restore and a menu will appear with the last 15 days of back-ups.

Select the date that you wish to Restore.

Firefox 67 and later can use a dedicated profile for each of the Firefox update channels and will lock the profile, so it can only be used by Firefox in a specific installation folder. For Release versions this profile would be a xxxxxxxx.default-release profile, profiles used in older Firefox versions usually used a xxxxxxxx.default profile (a refresh adds a time stamp).

• https://support.mozilla.org/en-US/kb/dedicated-profiles-firefox-installation
• https://blog.mozilla.org/2019/01/14/moving-to-a-profile-per-install-architecture/

You can open the about:profiles page via the location bar to check whether multiple profiles are present and what profile Firefox currently is using.

• Do NOT click any Remove button on this page.
• https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles

See also "Determine if Firefox has created a new profile":

• https://support.mozilla.org/en-US/kb/recover-lost-or-missing-bookmarks

[v57+] Places Maintenance is built into Firefox.

Type about:support<enter> in the address bar.

You will find Places Database near the bottom. Press the Verify Integrity button.

When done, copy and post the results here.