If your dough isn't rising properly after multiple hours, it could be because of the type of dough you've made, inactive yeast, or the temperature of the room. Some doughs just take longer to rise, so try leaving it for longer and put it in a warmer area of your home.

What do you do if yeast doesn't rise?

Add more yeast.

Open a new package of yeast, and mix a teaspoon of yeast with 1 cup (240ml) of warm water (at about 110°F/43°C) and 1 tablespoon of sugar. Let this mixture proof for about 10 minutes, until it gets 1/2- to 1-inch of foam. If this fails, you will need to get fresh yeast and try again.

Can I still use dough that didn't rise?

If your dough hasn't risen, then it's not worth baking it as it is or it'll be too dense to enjoy. Instead, you can roll it out very thin and bake it as a flatbread or a pizza. Alternatively, you can dissolve more active yeast in some warm water, then work it into the dough and see if it rises.