Repairing Damaged House Wiring?

I was changing a light fixture in the oldest end of my house. I decided I was going to use a long wood screw, in place of one of the mounting bracket screws to hold the fixture to the junction box. I was told that I could wire this fixture without flipping the main, by simply turning it off at the wall. I believe they called this hot-wiring. Long story short, I ended up going through a wire I guess. I know that the wood screw was malformed and soldered together end-to-end from the arc and pop.

My problem is, since this has happened, one whole wall, along with my bathroom, which is on the same adjacent wall, and washroom electricity has now been out for a month, all except for my dryer which runs off 220. I understand that it stands in a class of its own. What have I done? I flipped every breaker the breaker was actually never thrown. The breaker that runs this part of the house does not appear to be tripped after testing it numerous times. There is absolutely no power in plug-in outlets or light fixtures. Please help. I am tired of using extension cords to light my bathroom and run my washer. Can I fix this myself?