The stroke obviously did not affect the Hippocampus region of here brain which is memory storage and spatial navigation. As a rule, regions of the brain such as the temporal and the occipital all occur on both hemishperes of the brain, thus their ability to function seperately. Since here stroke only cut off the left hemisphere, the hippocampal region on the Right hemisphere remained intact, and so did her memory.
As a response to the last part of your post, the Right brain defines self existence. The left brain defines self individualism. The Right hemisphere acknowledges your sense of life and sensory perception, and the Left hemisphere defines where the boundaries of your perception are... ie. where your hands stop, the color range, tonal range and the reasons WHY.