This morning I woke up to my house feeling colder than normal. I looked at the thermostat and even though the house was still set at the typical temperature, it was 10 degrees colder. The furnace seemed to be blowing cold air. So I turned the thermostat off so that I could go look at the furnace without being nervous or scared, but the fan only kept running (no off option for the fan on my thermostat). I figure out how to turn the furnace fan off once downstairs, but that's all I figured out. It's a gas furnace but I don't see a pilot light or even where the pilot light would be, except maybe inside this box that has a window. I know nothing about furnaces, and I just bought my house in October, so haven't looked at the furnace really. The furnace only says "Enviro Plus 90" and "RJII" on the outside, so I do not know who made it. I tried looking at other questions on here, but none of them helped since I see no green or red lights anywhere. Any advice before I call someone to help me who looks at me like I'm an idiot and paying for something I am sure I should be able to fix on my own?

Turn all power back on to the furnace, wait 5 minutes and then look into that small window you noticed inside the box. There should be some small lights showing a code. Could be one or two green lights either flashing or steady, do you see them? You will not actually see a pilot light ever on this furnace. Today's furnaces do not have pilot and employ either a spark igitor or glow coil