Hello,

Sorry to hear about that. First, Firefox automatically creates backups of your bookmarks, which can be helpful if your bookmarks are lost or missing.

1. Click the Bookmarks button Bookmarks-29 (or New Fx Menu > Bookmarks) and select Show All Bookmarks.
2. At the top of the Library window, click on Import and Backup and select Restore.
3. Click the date of the bookmark backup you want to recover.
4. In the new window that appears, click OK.

   Your bookmarks from the selected date should now be restored. 

If the above doesn't work, it could be that a file got corrupted (namely the places.sqlite file). You can install the Places Maintenance extension to run maintenance on the file. Please read the following articles first as they provide helpful hints and instructions that may be relevant to you:

   http://kb.mozillazine.org/Bookmarks_history_and_toolbar_buttons_not_working_-_Firefox
   https://support.mozilla.org/kb/Bookmarks+not+saved#w_fix-the-bookmarks-file 

Did this fix your problems? Please report back to us!

Thank you.

Make sure you install Firefox properly.

Open the Firefox Disk Images file and drag the Firefox application to the Applications folder on your hard drive. You shouldn't double-click the Firefox application to run it from the Disk Images, but instead drag it out of the DMG folder.

• https://support.mozilla.org/en-US/kb/install-firefox-mac

- - - -

If you lost personal data then it is possible that a new default-release profile folder has been created. See "Determine if Firefox has created a new profile":

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