I'm by no means a Finale expect (I prefer Sibelius) but...
Perhaps your printer doesn't support the "jazz" font? Changing font for this piece could possibly have changed the font for every piece which would explain their sudden decline into gobbledegook... Try changing font back to whatever it was before and see whether that fixes it.
Apart from this you could have a bad connection between your computer and PC, a corrupted printer driver, or some nasty little virus
, but I suspect you'd see prolems with all your printing, not just Finale if that were the case.
Let's hope it's just the font!
Jan.