To retrieve lost bookmarks, undo the action that resulted in the loss by selecting the Undo option from the Organize menu, import the backed up bookmarks from an HTML file if you created one earlier, or rename the existing BAK file by removing the .bak extension so that the browser uses it by default. Make sure to back up the bookmarks you created after losing the old ones because these processes restore the bookmarks to an older state.
To restore bookmarks In Firefox, open the Firefox menu, select the Bookmarks option, click on the Organize button, and select the Undo option. Alternatively, press Control and the Z key at the same time immediately after losing the bookmarks. The downside of this method is that it can’t retrieve lost bookmarks if you close Firefox prior to restoring them. To retrieve bookmarks from a backup file, click on the Import and Backup button, hover over the Restore option, select one the backup files that Firefox created automatically, or choose a custom file.
In Chrome, import an existing backup file, or access the AppData folder for Chrome that contains the Bookmarks.bak file. To do this, press the Windows and R keys at the same time, type “appdata” in the field, click OK, and then open the Local, Google, Chrome, User Data and Default folders. Delete the Bookmarks file, right-click on the Bookmarks.bak file, select the Rename option, and delete the .bak extension.