Why did my dough not rise?

The answer

The most common cause of dough that will not rise is yeast that is old or dead, followed by water that was too hot, a cold room, or too much salt. Test the yeast in lukewarm water of about 110°F (43°C) with a pinch of sugar and look for foam within 5 to 10 minutes. Then check that the water was not above 120°F (49°C), move the dough somewhere gently warm, and confirm the salt was measured correctly. Work through the causes in that order.