Sound, no picture. When I play a DVD, the sound is audible, but there's no picture. I suspect it's

Question

When I play a DVD, the sound is audible, but there's no picture. I suspect it's a problem with the settings. However, I cannot get to the "blue screen" with all the menu options. So all I can do is randomly press buttons on my remote. (Wife was poking some buttons on the remote and this problem occurred; in the past the DVD player worked just fine.)