If you notice you lost bookmarks or accidentally deleted bookmark(s) and you haven't closed Firefox yet then you can use "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 stack of changes to bookmarks for the current session). Otherwise you can consider to restore the bookmarks from a JSON backup in the bookmarkbackups folder. *Bookmarks -> Show All Bookmarks -> Import & Backup -> Restore This will replace all current bookmarks and you lose bookmarks that were added since that backup was created, so you may want to create an HTML backup beforehand. ---- Note that on Mac you only have icons in the Library on the toolbar. *Organize is the first of the three buttons next to Back and Forward. *Views is the second button. *Import and Backup is the third button. See also: *https://support.mozilla.org/en-US/kb/bookmarks-firefox