Hi, as a starting point, you can have Firefox create a new profile while you search for your data. There is a support article on that: [[How to run Firefox when your profile is missing or inaccessible]]. It will be a new user experience, but at least you'll be able to use some built-in tools. I'm not familiar with the process your Windows went through. Two initial questions: (1) Are you still running an installation of Firefox that you downloaded from Mozilla's website or did you switch to the one from the Microsoft Windows store (that one uses different paths)? (2) In certain major changes, Windows moves your old content to a temporary backup folder named C:\Windows.old Do you have that folder? If you do see that folder: Set Windows to show hidden files and folders -- this Microsoft article has the steps: https://support.microsoft.com/en-us/windows/view-hidden-files-and-folders-in-windows-97fbc472-c603-9d90-91d0-1166d1d9f4b5 Then explore that folder up to this point (if it exists): C:\Windows.old\Users\<username>\'''AppData\Roaming'''\Mozilla\Firefox\Profiles\ If you find recent data there, please pause and we can suggest how to restore that profile data.