It happened about an hour ago. My phone suddenly went to 3G, so I used *#*#4636#*#* and tried changing it to LTE only and it would only show the no signal icon on my phone. I know I'm in a 4G area, my son's phone has 4G and it's working fine, but this one isn't. I'm not paying 45 dollars per phone for bad service quality.
Have you tried turning off the phone, removing the SIM card, waiting a few minutes, putting the SIM card back in, rebooting the phone, then allowing the phone to establish a fresh network connection? If that doesn't work and there are no tower issues in the area, you might try a new SIM card (they're free at your local Corporate Verizon store).
Don't do it! You run the risk of loosing the use of WIFI with Jelly Bean.
Everyone I know including myself have lost the use of WIFI after Jelly Bean.
Verizon Support says upgrade your router. I can't upgrade every public router. And my home router is provided by Verizon and they tell me it is the most current. So their response is to buy a new phone.