Sorry to hear about this problem. If you have a few more minutes to look for your data: Do you recall either of these around the time of your update: (1) Firefox suggesting that you perform a tune-up or Refresh to speed up Firefox? => Look for an "Old Firefox Data" folder on your Windows desktop. If you find this folder, let us know and we can suggest how to recover data from it. (2) Firefox saying it needed to create a new profile? Normally this only happens for downgrades, but I suppose anything is possible. ---- ''If neither of the above:'' If you haven't already, could you close out of Firefox and do a normal Windows shutdown and restart to complete any pending updates and release any file locks. If Firefox again starts up without your data, could you check whether your stuff is available in a different profile, as follows: '''Profile Manager Page''' Inside Firefox, type or paste '''about:profiles''' in the address bar and press Enter/Return to load it. This page should list at least one profile and could list many. (Each profile has two folders and one or more buttons. Do not use any Remove buttons!) The profile that Firefox is currently using will have this: '''This is the profile in use and it cannot be deleted.''' Do you have any other profile(s) listed on this page? If so, you can check whether it is the one you were using recently by clicking its '''Launch profile in new browser''' button. If it isn't what you want, simply close that new window. If it IS what you want, back on the about:profiles page, click the '''Set as default profile''' button for that profile so Firefox uses it automatically at the next startup. Any progress so far?