I know on Twitter yesterday that there was an outage in the Essex area which affected NOW and Sky Broadband customers.
Not sure if it's resolved or not.
I am guessing you have tried a power reboot on your Router by unplugging the power to it for 2 minutes to see if the internet comes back on.
Anyway your best option is to phone the NOW Broadband Team using the telephone number on this link page below.
Call the broadband team to find out what’s going on. Nothing will be posted or updated by staff on the customer forum.