Just turned on tv, blank screen, channel numbers don't show on box, nothing. Turned back off and on again, everything is same as last time tv was on yesterday, nothing works. Called customer service, they couldn't help. I guess it's the 'upgrade'. Any ideas? Thanks.
Is your cable box "on"?
...or a dog or cat that may have unplugged the cable box from the outlet? Maybe the HDMI cable got disconnected?
If the box and tv are both powered on and the tv is on the correct input and still getting the same results, you either have a faulty box or faulty tv.
There are a number of reasons you might be seeing this.
If you change inputs on the TV do you get anything? Do you have a DVD or gaming system you can try to verify it is not the TV set? If you get picture and sound on something else plugged into the TV I would try moving the cable box to that input and testing.
Has the cable box been unplugged and plugged back in?
Can you tell if either of the devices are actually turning on?