Cool air or old yeast will keep your bread dough from rising properly. If a bit of heat doesn't revive the yeast, you can mix a little more yeast into the dough.
Create a warmer place for the dough: Fill a large pan with boiling water and place it in the oven on the lowest rack, or heat a mug of water for 2 minutes in a microwave.
Place the dough (in its bowl) in the oven or microwave along with the hot water. Leave it to rise.
If the dough still doesn't rise, add more yeast. Mix yeast from a new package with 1/4 cup (2 fl oz/60 ml) warm water and 1/2 tsp. sugar. Let it sit for 10 minutes until foam forms, to be sure the yeast is active.
Knead the yeast mixture into the dough.
Leave the dough in a warm place to rise.
If you have no more yeast, turn the dough into tasty crackers or breadsticks: Knead with grated cheese, roll thin, sprinkle with salt and black pepper, cut into squares or thin strips, then bake at 325Ã‚Â°F (165Ã‚Â°C) for 10 minutes or until golden brown.