If you were using the Bookmarks Toolbar for quick access to your favorite bookmarks and the toolbar is now missing, you may have turned off the option to display the Bookmarks Toolbar. To turn it back on:

   Right-click on an empty section of the navigation bar and select Bookmarks Toolbar in the pop-up menu. 

For more information, see the Bookmarks Toolbar - Display your favorite websites at the top of the Firefox window article.

What about the rest of your profile? Settings, bookmarks, history, passwords . . . .

Look on your desktop. Do you see a folder called; Old Firefox? Look inside.
Look for the folder with the latest creation date.

https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile

https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles

https://support.mozilla.org/en-US/kb/how-run-firefox-when-profile-missing-inaccessible

https://support.mozilla.org/en-US/kb/how-run-firefox-when-profile-missing-inaccessible

http://kb.mozillazine.org/Profile_folder_-_Firefox#Navigating_to_the_profile_folder

https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles

https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles

Type about:profiles<enter> in the address bar.
How many profiles are listed?
How many should be there?
Also, open the profile folder in your file explorer.