bread batter

If you leavened it with baking powder, it should be fine. The beauty of double-acting baking powder is that it contains two acids. One reacts with water, the other with heat, to produce carbon dioxide, which then leavens the batter. It's especially relevant to batters which are retarded before baking, such as pancake and muffin batter in restaurants. And if you used baking soda, it has likely expired by now. However, if you sift over the top additional of the original amount called for, along with a couple of tablespoons of flour, then stir it in, you should still be fine. It's all a science experiment!

My guess is that it might not rise correctly, as quick breads often rely on a reaction between leavening (baking soda or powder) and some sort of acid (yogurt, buttermilk). That reaction would've come and gone by now.
But, I suggest you bake it and find out!