Hi, you can try this: Open bookmarks > Show All Bookmarks > Import and Backup > Restore, and see if you have a backup there from before the deletion.

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note that if you haven't closed Firefox yet then see if you can use "Organize > Undo" in the bookmarks manager (Bookmarks > Show All Bookmarks) to undo this action and restore the bookmark(s). The Organize button is the first of the three buttons next to the Back and Forward buttons on the toolbar in the Library (Bookmarks Manager). If it didn't work then you can restore the bookmarks from a JSON backup in the bookmarkbackups folder.

The name of a JSON bookmarks backup file includes a total item count (folders and separators included) and an hash value to prevent saving the same backup more than once. That way you can see if there is a change in item count and can select a recent backup that has all bookmarks and folders.

• bookmarks-YYYY-MM-DD_<item count>_<hash>.jsonlz4

If there is a problem with restoring a backup then you can check for problems with the places.sqlite database (bookmarks and history) in the Firefox profile folder.

• https://addons.mozilla.org/firefox/addon/places-maintenance/

See also:

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