I have to make brownies but I am abt 3 tablespoons short of flour, can I replace it with all purpouse flour or should I make the brownies with the less amount of white flour that I have..
Sure, use all-purpose flour.
I don't know what your original recipe said, or what exactly your non-all-purpose white flour is, but all-purpose flour is normal, regular flour, exactly what a brownie recipe that calls for "flour" would normally mean. Even if there is a difference here (e.g. cake flour vs all-purpose flour) a few tablespoons in brownies is not going to be a big deal.