how do i change just the bulb on a 1999 ford escort sport

well you can buy the bulb so it seems to me that you have to be able to change it without changing the whole headlight. best of luck to you

you tube has many instructional videos on car maintenance

Not true on my car. I had to remove the whole plastic backside to my light and then it became obvious how to remove the bulb from the backside. Buy a bulb for you and buy a bulb also to brighten up the brain of whoever gave you expensively bad advice.