If you lost personal data then it is possible that a new default-release profile folder has been created.
See "Determine if Firefox has created a new profile":

• https://support.mozilla.org/en-US/kb/recover-lost-or-missing-bookmarks

You can open the about:profiles page via the location bar to check whether multiple profiles are present and what profile Firefox currently is using.

• Do NOT click any Remove button on this page.

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

Have opened the Old Firefox Data folder and copied over the files suggested to the current Profiles folder. Still getting the Bookmarks and History function error message.

Please provide a screenshot of that error message.

https://support.mozilla.org/en-US/kb/how-do-i-create-screenshot-my-problem

Then use the Add images -- Browse .... button to submiy that screenshot.

If you use Sync then best is to disconnect Sync temporarily during troubleshooting.

You can check for problems with the places.sqlite and favicons.sqlite files in the Firefox profile folder.
*use "Verify Integrity" button on the "Help -> Troubleshooting Information" (about:support) page If errors are reported with "Verify Integrity", close and restart Firefox and retry.

If "Verify Integrity" cannot repair places.sqlite, rename/remove all places.sqlite and favicons.sqlite files in the Firefox profile folder. Firefox will rebuild places.sqlite and restore the bookmarks from a recent JSON backup in the bookmarkbackups folder.

• keep a backup copy of places.sqlite in case a new places.sqlite database has to be created

See also:

• https://support.mozilla.org/en-US/kb/Bookmarks+not+saved#w_fix-the-bookmarks-file
• https://support.mozilla.org/en-US/kb/fix-bookmarks-and-history-will-not-be-functional

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