Solder any severed connections. I recommend referencing How To Solder and Desolder Connections for how to do this!

If necessary, you may have to strip some of the casing to expose enough of the wires to be able to reconnect them. You can get away with using scissors if nothing else, but I recommend using a wire stripper for this purpose, as instructed in Wire Stripping.

Solder is a toxic substance, so do not inhale it. Do not eat or drink anything after handling solder until after you have thoroughly washed your hands.

The wires will get hot very quickly on contact with the iron, so be quick and careful not to burn yourself.