We just had the same problem, and just happened on a solution:
Press DISPLAY
Go to OTHER and press enter
Go to OTHER (on new list) and press enter
SETUP should be highligted, press enter
Go to OTHERS and press enter
Go to REINITIALIZE SETTINGS and press enter
Go to YES and press enter
after our Panasonic DVD-LS91 (portable) fell off a footstool while in operation, the audio works,...
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after our Panasonic DVD-LS91 (portable) fell off a footstool while in operation, the audio works, but not the video--we see nothing on the screen except a change in the shade of gray when switched from off to on.