Is the bookmarkbackups folder entirely empty?

You can use this button to go to the current Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder

See also:

• http://kb.mozillazine.org/Recovering_a_missing_profile

Do you have an "Old Firefox Data" folder on the desktop?

When you use the Firefox Refresh feature then a new profile is created and some personal data (bookmarks and history, form data, tabs) is automatically imported. The current profile folder will be moved to an "Old Firefox Data" folder on the desktop. Installed extensions and other customizations (toolbars, prefs) that you have made are lost and need to be redone.

It is possible to recover data from the "Old Firefox Data" folder on the desktop, but be cautious not to copy corrupted files to avoid carrying over problems.

• https://support.mozilla.org/kb/Recovering+important+data+from+an+old+profile
• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

Separate Issue; Your System Details shows;

Installed Plug-ins

Adobe PDF Plug-In For Firefox and Netscape 11.0.16 Adobe PDF Plug-In For Firefox and Netscape 15.16.20039
Having more than one version of a program may cause issues. You must remove the older programs. Then get the current full installer.

Adobe PDF Plug-In For Firefox and Netscape: Adobe Reader Version 2015.016.20039 Note: Other Software is offered in the download.

These can't get your data back, but will help in the future.

These add-ons can be a great help by backing up and restoring Firefox

FEBE (Firefox Environment Backup Extension) {web link} FEBE allows you to quickly and easily backup your Firefox extensions, history, passwords, and more. In fact, it goes beyond just backing up -- It will actually rebuild your saved files individually into installable .xpi files. It will also make backups of files that you choose.

OPIE {web link} Import/Export extension preferences