Without more info like version of photoshop or photoshop elements, operating system, color mode of the image, etc, i'd say to check the Auto Color Correction Options>Target Colors.
Make an Levels adjustment layer and in photoshop select Auto Options or in Photoshop Elements Alt or Option click on the Auto button
The default colors are
(click on the color chips to change)
Shadows RGB 0,0,0
Midtones RGB 128,128,128
Highlights RGB 255,255,255
I tried your fix and it worked. Thank you very much for relieving my frustration. There was nothing in any of the 5 Photo Shop books that I have purchased.