Bookmarks and history and downloads are stored in places.sqlite in the Firefox profile folder.

Did you lose other data ? Did you already reboot the computer ?

See:

• https://support.mozilla.org/en-US/kb/recover-user-data-missing-after-firefox-update

You can check if you have an "Old Firefox Data" folder on the desktop in case the Refresh feature in Firefox has been used and a new profile has been created.

• https://support.mozilla.org/en-US/kb/reset-firefox-easily-fix-most-problems

If you use the Time Machine or other backup then try to restore file(s) from this backup.

• https://www.apple.com/support/timemachine/
• https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data
• https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile

Location used for the main profile that keeps your personal data (Root Directory on about:profiles).

• ~/Library/Application Support/Firefox/Profiles/<profile>

In Mac OS X v10.7 and later, the "~/Library" folder in the Home directory is a hidden folder.

• https://www.macworld.co.uk/how-to/mac-software/hidden-files-mac-3520878/

I did not seem to lose any other data. Yes I have already rebooted. I do have an Old Firefox Data and Relocated Items folder on the desk top. I have tried some of the links provided. None have worked

You can copy certain files with Firefox closed to the current profile folder to transfer or recover personal data.

• bookmarks and history: places.sqlite
• favicons: favicons.sqlite
• bookmark backups: compressed .jsonlz4 JSON backups in the bookmarkbackups folder
• cookies.sqlite for the Cookies
• formhistory.sqlite for saved autocomplete Form Data
• logins.json (encrypted logins;32+) and key4.db (decryption key;58+) for Passwords saved in the Password Manager
  key3.db support ended in 73+; to use key3.db in 58-72, make sure to remove key4.db
• cert9.db (58+) for (intermediate) certificates stored in the Certificate Manager
• persdict.dat for words added to the spell checker dictionary
• permissions.sqlite for Permissions and possibly content-prefs.sqlite for other website specific data (Site Preferences)
• sessionstore.jsonlz4 for open tabs and pinned tabs (see also the sessionstore-backups folder)

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

• Help -> Troubleshooting Information -> Profile Folder/Directory:
  Windows: Open Folder; Linux: Open Directory; Mac: Show in Finder
• https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data