Xenon lights not coming on

[Elliot182]

Both headlights won't come on? Before I buy any bulbs is there common faults or a check I can do. All other lights work

 

[JCC]

Passenger footwell, underneath the dash just next to the door, there are 4 little black boxes called relays that should be plugged in up there. One of them will be loose or have fallen out most probably.