The right front low beam headlamp on my 2009 Lincoln MKZ doesn't work.
Check for a loose or bad ground, repair, clean as necessary, the bulb itself could be burnt out again, when replacing the headlight bulb use a rag or something as too not touch the glass of the bulb, as the oil from your hands heats up on the bulb causing it to burn out prematurely.
And check headlight relay should be one for each side and possibly high and low beam
HID headlight may have an HID ballast issue.
More info.....http://www.2carpros.com/questions/2009-lincoln-mkz- headlight
Looking for a Used MKZ in your area?
CarGurus has 198 nationwide MKZ listings starting at $4,495.
Search Lincoln MKZ Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
Lincoln MKZ Experts