Pmalito, by default Firefox on Windows stores profile folders in the following directory: C:\Users\<your Windows login username>\AppData\Roaming\Mozilla\Firefox\Profiles\ You may need to adjust this path to allow for the old hard drive not being drive C on your current computer. You could also try to find your original profile folder by searching the old hard drive for certain files that a Firefox profile will often contain, such as "places.sqlite", "favicons.sqlite" "formhistory.sqlite" etc. For more information on profile folders and their locations, see: https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data For more information on the files that are often found in a profile folder, and their uses, see: https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile#w_your-important-data-and-their-files