No, maybe possible to get them, maybe not. Info plus how to and if have issues recovering from the your Profile we can try to help further. If your bookmarks are on another computer/phone do not sync until make a backup to HTML then have a long, long time. Try : https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data and https://support.mozilla.org/en-US/kb/recover-lost-or-missing-bookmarks and https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile and https://support.mozilla.org/en-US/kb/how-run-firefox-when-profile-missing-inaccessible and need to learn this one for Export and other import and your set. https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer and https://support.mozilla.org/en-US/kb/import-bookmarks-html-file

Please let us know if this solved your issue or if need further assistance.

Are you sure that your bookmarks are really gone?

The main bookmarks button for a menu drop-down in Firefox 57 is truncated and doesn't show any bookmarks folders, just Recent Highlights. There is also a multiple panel slider menu setup that is operated by the > & < (arrows) for the menu items to view the various menu for each menu item that appears.

Very different from previous versions - but that can easily be corrected.

Open the Bookmarks Sidebar using {Ctrl + B} or via the Show Sidebars button and see if your bookmarks are there. Or you can hit the Alt key to open the Menu Bar and use the Bookmarks menu there to see if your bookmarks are there.

To "restore" the previous type of Bookmarks drop-down menu see this support article. https://support.mozilla.org/en-US/kb/bookmarks-firefox#w_how-do-i-add-the-bookmarks-menu-button-to-the-toolbar Or if you are familiar with using the Customize feature for the Toolbars, open it and drag the Bookmarks Menu button to the Toolbar. That button has a Star above a "tray.