Why won't my HDTV pick up any channels all of a sudden after an internet repair?

Comcast came to check out the internet because it was acting up. A few hours later we tried to watch TV (we don't have cable, but have HD TVs so they pick up the standard free digital channels through a coaxial cable) and none of the channels worked. We did a channel scan and it found zero analog and zero digital channels. What happened? Did Comcast put a block on our TVs because they're mad that we don't pay for cable???