For bookmarks you need the old files ''places.sqlite'' and ''favicons.sqlite'' and the folder ''bookmarkbackups''. You can recover data from the folder named Old Firefox Data on your computer desktop with Firefox closed. https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data#w_finding-your-profile-without-opening-firefox

There's a file named "old bookmarks"? I don't think that's a standard Firefox file. Are you sure that's the exact name? Also, did you try the steps in the following article: [[Recover lost or missing Bookmarks]]