if all purpose flour is not available,what can i use in place of it?

It depends what you are baking...but for the most part cake flour is an ok substitute

In a pinch, you can use cake flour, which just has a small amount of cornstarch sifted into it. You could use self-rising flour as well, but decrease the baking powder and salt in the recipe as they're already sifted in.

Spelt flour, white whole wheat flour, or white whole wheat pastry flour, are also all options, although they will make a slightly heavier end product. But really all-purpose flour is the best choice!