How do you put the headlight back in the 2003 vw beetle?

Persistence. The slide assembly used for these headlights is ingenious and infuriating at the same time. Make sure that the lugs are matched up to the slots that they go through. Gently but, firmly move the light assembly into the socket assembly until it stops. Turn the lever to pull the light assembly back into place. Wiggle the light assembly while turning the lever to help it go smoothly. If it does not go the first 2 or 10 times, do not get frustrated. It will go and the next time you have to change one out it will take 1/10th of the time.