The headlight bulbs on 1999-2005 VW Jetta can be accessed behind the headlight assembly in the engine compartment, open the hood and detach the headlight cover retaining clips as shown in the image.
Next, remove the rear plastic headlight cover.
Unplug the headlight bulb electrical plug by pressing on the plastic tab located underneath the connector and gently pulling away from the bulb at the same time.
Remove the round headlight bulb retaining clip by turning it counterclockwise about 35 degrees to unlock it, once it is unlocked pull it out and set it aside, pay attention to which way it came out, it will need to be installed back on the vehicle the same way.
Pull the headlight bulb away from the headlight housing.
Make sure that you don't touch the glass on the new headlight bulb when installing it on the vehicle, if you touch the glass part the life of the bulb will be reduced.
Install the remaining items in the reverse order they were removed, turn the headlights on and make sure that both low and high beam headlights work.