When you use the Reset feature, Firefox moves your old settings to a file on your desktop named Old Firefox Data.

Can you find that folder?

There isn't an easy way to switch that folder back into operation, but if you are fairly patient, I've posted my suggested procedure in this thread: when using restart firefox you get a folder on the desktop called old firefox data i need to know how to use this folder to get my old firefox preferences back.

Does that help?

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 backup of files that you choose.

OPIE {web link} Import/Export extension preferences