My Android thinks part of the screen is being pressed - solution?

[AC Question]

I have an LG Volt. It's no contract, so there's no warranty, which means I'm on my own. I don't know exactly what happened, but I stopped using my phone for about 30 minutes. When I tried using it again, it started acting really weird. I can't change screens, and I can't power off (when I hold down the power button, the restart options show up, but clicking on them doesn't do anything). I finally managed to open the programs in my bottom row, but, when I click on them, the app store will open first, and I can only get into the other app once I close the app store. When I type, the letter "j" appears after every letter, (e.g.: ijpj.jxjaj). So I think the phone thinks it's being constantly pressed in the app store/"j" region, but I have no idea how to fix it. I can't get into settings, because when I push that, it thinks I'm pushing theme (which is in the same location as the app store/letter j. Does anyone know what's going on or how to fix this?