Firefox keeps 10 automatic backups of your bookmarks. Restore one of those if it was created before the problem occurred, but after your most recently added bookmark. * [[Restore bookmarks from backup or move them to another computer]] ---- If not, # Create a manual backup of your bookmarks (see the same support article above for details). # Run a full check with the Places Maintenance add-on. #* https://addons.mozilla.org/firefox/addon/places-maintenance/ ---- If that doesn't help, # Create a manual backup of your bookmarks. # Export your bookmarks in HTML format. #* [[Export Firefox bookmarks to an HTML file to back up or transfer bookmarks]] # Open the exported ''bookmarks.html'' file in a text editor like [http://notepad-plus-plus.org Notepad++]. Notepad included with Windows should work, if you absolutely have to use it. For technical reasons that aren't worth getting into, Notepad++ is preferable. # A bookmark entry is an <nowiki><A></nowiki> element nested inside a <nowiki><DT></nowiki> element that has no closing tag. This is what you want to delete: start at <nowiki><DT></nowiki> and stop at the nearest <nowiki></A></nowiki>. See the attached screenshot for an example. # Once you're done editing, save and close the file. # Press Ctrl+Shift+B to open the Library, then delete all your bookmarks (importing from HTML appends bookmarks to the current list, so you'd end up with a ton of duplicates otherwise). # Import the modified ''bookmarks.html'' file. #* [[Import Bookmarks from a HTML file]]

Problems with bookmarks and history not working properly can be caused by a corrupted places.sqlite database file. You can check for problems with the places.sqlite database file in the Firefox profile folder. *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