First try to reset Firefox printer settings, if you are still unable to print you can then reset all firefox printer settings.

Reset firefox printer settings:

1. In the Location bar, type about:config and press Enter.

2. In the Filter field, type print.print_printer.

3. Right-click on the print.print_printer setting and select Reset.

4. At the top of the Firefox window, click on the Firefox button (File menu in Windows XP) and then click Exit.

The first way was just simple reset of firefox printer settings. However, if it failed to solve the problem then you need a full reset of all firefox printer settings.

1. Open your profile folder: At the top of the Firefox window, click on the Firefox button, go over to the Help menu (on Windows XP, click on the Help menu) and select Troubleshooting Information. The Troubleshooting Information tab will open.

2. Under the Application Basics section, click on Open Containing Folder. A window with your profile files will open. Note: If you are unable to open or use Fire​fox, follow the instructions in Finding your profile without opening Firefox.

3. At the top of the Firefox window, click on the Firefox button (File menu in Windows XP) and then click Exit.

4. In your profile folder, copy the prefs.js file to another folder to make a backup of it.

5. Open the original prefs.js file in a text editor (such as Wordpad).

6. Remove all lines in prefs.js that start with print. and save the file.

See:

Fix printing problems in Firefox

The first thing to do is to locate the Print button on that web page or "Printer Ready" button on that web page. You need to see a "page" which shows only that one email, without the site navigation menu showing on the left side of the page, so that Firefox only prints that email and not everything you are now viewing.

this is way to technical, what caused it when everything was fine and get up and it doesn't work. there has got to be another way