Firefox keeps your personal information including bookmarks in a set of files, which are called profiles. The Firefox profile is stored separately in a location from the Firefox program files. The default location of the Firefox profile on your PC is C:\Users\Username\AppData\Roaming\Mozilla\Firefox\Profiles\; that’s where your Firefox bookmarks are stored. It remains the same from PC to PC unless you change the Firefox bookmarks location manually.

OK - thanks - I found the files - now what do I do?

There are 3 files with today's date on them - I thought I wanted yesterday's files before I made the mistake.

Firefox automatically backs up your bookmarks and saves up to 15 backups in the profile bookmarkbackups folder. To recover bookmarks that were previously saved in the Bookmarks menu or on the Bookmarks toolbar but are now missing, you can restore them from one of these backups:

1. Click the menu button to open the menu panel. Click Bookmarks and then click the Manage Bookmarks bar at the bottom. 2. In the Library window, click the Import and Backup button and then select Restore. 3. Select the backup you want to restore from the list of dated automatic backups. You can also select Choose File… to restore bookmarks from a manual backup, if you created one. 4. After confirming your choice, the bookmarks from the backup you selected will be restored.

In some cases, Firefox may create a folder on your desktop called "Old Firefox Data". This folder contains a complete backup of your Firefox profile and can be used to restore bookmarks and other missing information. If you have this folder on your desktop, see Recovering important data from an old profile.