VoltVoltVolt

The other day I went to install Forge, and accidentally set my always open with to a ZIP extractor, which I don't remember if that's supposed to happen or not, and I've tried opening it with other things, which only brings up the files (Is there something I should open in there?), and re downloading it, but I'm not too good at these kinds of things and I need a certain mod for a class by Friday. Any help?