PHOTOSHOP Paint Brush / New Layer / Photo Editing Issue

I am designing a flyer and need to edit unwanted parts in the photo. I normally use my paint brush by setting the color black and white. As i switch colors, black to erase/ white to replace... This tool as i add more feather and size to the paint brush, i can mix and blend as i wish.

I am not sure why i am unable to do this for sometime now.

I have checked:

1. The black and white color.
2. feather and size paint brush
3. file of the photo JPEG

This is a very simple feature that has become very challenging to resolve. I need help.