make yourself a yeast starter. You'll never need yeast again. You don't need yeast to start a yeast starter…do it the OLD way.
Mix 1 cup flower, 1 tsp of sugar and enough water to make a thick paste.
Leave the bowl sit out uncovered. preferably near a window that is open sometimes, and in the sun, and warm. It will take longer if you can't, but that's all.
check it over the next few days. When it starts to show bubbles, that means naturally occurring airborne yeasts have found it. Give it another day to sit out until the entire surface is well covered with bubbles, and when you sniff it you can smell the yeasty smell.
at that point, divide your mix in half. Find a glass jar, and put half in the glass jar with a little more water and flour, and stick in your refrigerator. And with the other half, use as your yeast to make bread.
You can hasten the process with fruits that have a dusty coating on them (WHICH IS YEAST) like grapes and blue berries and toss a few of those (as long as they have that dusty blush on them) into your mixture when you start. Fish them out before dividing your new yeast culture.