I was cutting the grass outside and accidentally cut through a brown wire leading to my outside ac. The brown wire actually contains 8 small wires and the two coming from the unit are yellow and black. How do I reconnect?

Yellow to yellow,, black to black

First kill the power to your outside and inside units and the stat. Peeling back the insulation should expose 8 different colors of wires and, like wmproop says, yellow to yellow, etc...