BLACK LEVEL MESSED UP

After my daughter unplugged up her playstation from the tv, the black level messed up.  I had to go into the Menu screen and turn the black level all the way to the right, contrast all the way up, and color and tint way down, and I still have trouble watching any show/movie that is done in the dark (you can't see a thing).  It's done this once before and I took it to the repair shop.  They fixed it and told me there's a reset button on the inside of the tv he had to push (charged me $75).  I would think this is something I can do myself if someone would tell me where it is.