Whether you can easily restore old data depends on what was deleted and how. For example, if folders were manually deleted, they might be available to restore from the Windows "Recycle Bin". If a cleaning tool was used, it may or may not have moved the files to the Recycle Bin (they might have been permanently deleted). ''If it's not available to be restored:'' Have you checked for shadow copies? See: Windows often makes backup copies of Firefox profile data when you do system updates, so you can use a tool like one of the following programs: * ShadowExplorer: http://www.shadowexplorer.com/ * Shadow Copy View: https://www.nirsoft.net/utils/shadow_copy_view.html Note that you should set Windows to show hidden files and folders before diving in: https://support.microsoft.com/en-us/windows/show-hidden-files-0320fe58-0117-fd59-6851-9b7f9840fdb2 Then within the most recent restore point shown in the program, you can explore along this path to see whether you can find a shadow copy of your profile: \Users\''your-user-name''\AppData\'''Roaming'''\Mozilla\Firefox\Profiles\''your.profile'' Check for the '''bookmarkbackups''' folder. The files in that folder should have their creation dates coded into the file names. You can export one or more recent files to your Windows desktop (the live one, not the one in the shadow copy). Then you can use the steps in the following article to restore it, rolling back your current set of bookmarks to the ones in the backup file: [[Restore bookmarks from backup or move them to another computer]] (Note: you can use "Choose File" to point Firefox to your Windows desktop where you exported the backup files.)