Historically, when I pressed ctrl + 0 in Photoshop, an image came to fill up the available window space within Photoshop. Now, ctrl + 0 causes the image to become roughly 3 inches tall. If the image is twice as tall as it is wide, it becomes roughly 1.5" x 3". If it is twice as wide as it is tall, it becomes 6" x 3". But it never fills up the entire window space, which is about 5". I don't know why the image is defaulting to this size, and it is too small to work with. Did I inadvertently change some setting? Is it possible to restore ctrl + 0 to make the image fill the available window size again?
Is the command still the one shown for View > Fit on Screen or could it have been changed with Edit > Keyboard Shortcuts?
Could you please post a screenshot with the pertinent Panels visible?