Snowy screen. Channels not working.

Over the summer, my dad switched from Dish to Directv. I turned the TV on but it had the snowy (black and white) screen. I pressed "Tv Input" on my remote to change it but none of the options worked. Also tried the "Auto Program" thing for digital and analog channels or whatever it's called. It used to work with Dish but I don't know what I'm doing wrong. I unplugged the Directv box, reset it, tried a bunch of random buttons on my remote and every option the menus had but still has the snowy screen or says "No signal available"