It sounds like Netflix has crashed on you then.
You'll have to get online with your computer, access your Netflix account, then deactivate and reactivate your TV set's connection to them.
I believe this is what you select now. They made some changes to their account pages, and this is where you find deactivate/reactivate --
When you do that, your TV should show you its activation code again. Reinstall it and it should fix the problem.
Now, if that does not work, I'll be honest with you. TV manuals, no matter what brand you buy, provide NOTHING on the Internet access, how to add/remove a widget/application and re-install it.
I had to look that up on my Samsung, within smart and then add/remove using the colored buttons.
I usually don't have to delete the old application, then access Samsung's Widget store and pick up a new Netflix Widget free of charge but it's there and I've added/deleted before.
I would expect Panasonic has the same setup.