For those experiencing the recent On-Demand blank screen/partial menu: I unplugged the cable box AND the modem for 30-45 seconds. Problem fixed!
You may have to reset the modem to reacquire the IP address, though in my case I did not. If none of that works for you, contact Verizon and tell them to re-send the signal. Start simple though; Just unplug the cable box for 30 seconds...maybe a minute to be sure it reset.
That might be all you need. Best wishes!