Not recognising the faces of others is the symptom known as
'prosopagnosia'. This is supposedly more common in disorders causing
lesions in the non-dominant parietal lobe of the brain. Not recognising
one's own face is 'autoprosopagnosia' or the 'mirror sign'. This can be a
distressing symptom in Alzheimer's disease, for instance, where the
patient misinterprets the image in a mirror as a stranger. Many other
neurological diseases can result in these symptoms which are part of the
more general class of symptoms resulting in difficulty in reconising a
variety of images - the agnosias.
Hope this helps