I feed mine about 1 cup of flour every other day to keep it going (on the counter). If I leave it for more than 72 hours, it gets cranky and refuses to work. I've rescued it a couple of times now - 3/4 cup flour twice a day. Takes four or five days to come back, maybe more.
I have also found that the less I pour out, the better action I get. Supposedly, the balance of acidity is thrown off - inviting contaminants. But I've never had a problem, knock on wood.
So feed more, more often, pour out less. I bet in comes back in a week.