To explore, you'll first need to turn on viewing of hidden files and folders: http://windows.microsoft.com/en-us/windows/show-hidden-files Did Windows create this folder: C:\Windows.old If so, look for '''C:\Windows.old\'''Users\''your-user-name''\AppData\Roaming\Mozilla\Firefox\Profiles Assuming you find one or more folders there, one of them most likely will have your earlier Firefox data. Any luck? We can describe how best to rescue data from that temporary location (Windows will delete it after 30 days). ---- If that doesn't exist, try a global search of your "C" drive for '''bookmarkbackups''' which is a standard Firefox folder. Hopefully you'll find more than just your new one.