Type '''about:support'''<Enter> in the address bar. Under the page logo on the left side you will see '''Application Basics.''' Under this find '''Profile Folder.''' To it’s right press the button '''Show Folder.''' This will open your file browser to the current Firefox profile. Now '''Close Firefox.''' Enter the '''bookmarkbackups''' folder. This is where Firefox makes backups of your bookmarks. Look for the '''jsonlz4''' file you want to restore (check the time / date / size). Right click on that file and select '''Copy.''' Now go back to the profile folder where you started. Rename the file '''places.sqlite''' by adding '''.old''' to it. Now right click in the folder and select '''Paste.''' The file you just pasted here, rename it to '''places.sqlite.''' After you are done, restart Firefox.