About one a week, I bake the equivalent of two commercial loaves of bread. I do keep a pot of sourdough starter "perking" on a kitchen shelf.
I feed my starter daily with about 1-2 tablespoons of flour, and therein lies this tail...
My flour comes from 20-25 pound bags AND I usually buy UNBLEACHED flour....
This time I didn't read the label and just grabbed the bag and went through checkout...
So now my sourdough starter will not "perk", there is no yeast action going on, no bubbling etc.
So the cure, which worked, was to peal a small, UNWASHED potato (size of an egg) and stir the peals into my starter jar.
Within one day (24 hours), the starter batch was back in action, bubbling nicely and smelling like good sourdough ought to smell.
I removed the potato peals at that point. I suppose I could have simply added them to the next batch of bread dough, but I didn't think about that until I'd thrown them into my herb bed as compost.
Hope this helps someone else who can't get sourdough to "start". I do believe (without actual rigourous testing) that the bleached flour does not have the necessary yeast. I will be more observant the next time I buy flour.