luckily for you you have a J reg, so the loom from switch to fusebox is seperate from the rest o the car loom, easy swap just make sure you get one from a 90spec MK2 Golf or Jetta

sort the reason it happened first though, my guess would be the dim dip resistor wires havd shorted on the chassis, its on the chassis near the driver side headligh, size n shape of a paclk o polos. follow the wires from it and you'll fined a 2 pin plug, disconnect this and check the wires havent rubbed thru anywhere elae. Then bin the resistor.
Other thing that can cause loom meltage is using the wrong headlight switch, there were at least 3 different switches so make sure the switch you use has the same number of pins as the headlight loom plug!