Harry Potter killed my directv

Hello, I have been searching for help to my problem on the forums with no luck. WIth my kids homes for a week from school, I'm really looking for help (not ashamed to admit I use the TV to retain some of my sanity).

The problem: My sons were watching Harry Potter on dvd last night. To get to the dvd player, one of them used the old (TV) remote to switch to the dvd input. They watched the movie, no problem. We go to watch tv today, big problem. I think the first person to try to watch this a.m. used the directv remote to return to the right input and now we have nothing but black screens. we can scroll through video 1/dvd, video 2, video 3/games, video 4, video 5/cable box, video 6, video 7 (which shows "no signal" in yellow in lower right corner) and an unnamed input that has a blue bar with "no signal" and "3" across the top.

I have tried resetting the receiver (both with the red button and unplugging it) and all the cables are the same as they were yesterday when everything was working fine. I feel like it's something with the input (maybe?) but not sure what.

I am fairly technologically ignorant (isn't that obvious?), but sure would appreciate any insight.

Thanks!