the print button with Win8.1 in any pages don't work, only empty papers
Many web pages contain a print button to print content. Since the upgrade to win 8.1 these buttons no longer work. in other browsers work the same pages properly.
Maybe use the Windows Print feature instead of Firefox Print. Open the Charms Bar and click devices. Click on a printer and then put the settings. Press print.
Many print buttons launch a new window with a reformatted page more suitable for printing. If the problem is with the new windows, it could be the Firefox pop-up blocker, or a pop-up blocker in an extension or external security software.
To manage the built-in popup blocker, see: Pop-up blocker settings, exceptions and troubleshooting.
To determine whether an extension is a likely culprit, you could test one of the problem sites in Firefox's Safe Mode. That's a standard diagnostic tool to bypass interference by extensions (and some custom settings). More info: Diagnose Firefox issues using Troubleshoot Mode.
You can restart Firefox in Safe Mode using
Help > Restart with Add-ons Disabled
In the dialog, click "Start in Safe Mode" (not Reset)
I just noticed you wrote "only empty papers" in your question. Did you see this support article: Fix printing problems in Firefox?