Firefox makes regular backups of your bookmarks, so hopefully recovery will be quick. (1) I recommend making a copy of those files in a safe place before the clock ticks forward another day. This is in case you need to go back all the way to the oldest one. You can open your current Firefox settings (AKA Firefox profile) folder using either * "3-bar" menu button > "?" button > Troubleshooting Information * (menu bar) Help > Troubleshooting Information * type or paste about:support in the address bar and press Enter In the first table on the page, click the "Show Folder" button. This should launch a new window listing numerous settings files and folders. Look for the '''bookmarkbackups''' folder and click into it. Copy the files to a safe location, such as your Documents folder. One way is to select all the files (Ctrl+a) then right-click > Copy. Next, click your Documents folder and right-click>Paste. (You're done with that window now.) (2) This article has the steps for restoring backups using Firefox's Library dialog (Ctrl+Shift+b): [[Restore bookmarks from backup or move them to another computer]] Frankly, if there is a battle for supremacy between two Firefoxes linked to the same Sync account, I'm not sure who wins, but since you now have a copy of your backup file in your Documents folder, if necessary, you can copy it to the other PC to restore there as well. Success?