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

If the high beam work on your assembly what's wrong with the low beam is it the whole assembly just because the high beam work in the low beam don't?

And I have replace the low beam twice but it still don't come on but the high beam do on the passenger side

Mine is doing the same thing. I’ve replaced the entire headlight assembly and the low beam on the passenger side still won’t work

Just took my 2008 MKZ in for the same problem. Low beam replaced twice, but burned out soon after. I was told water was getting in the headlight assembly, causing rust and corrosion on bulb. Could replace the whole assembly, or drill two holes at base of assembly to allow water to drain out. Very small holes, not visible. Chose that option. Will have to replace assembly, if drains don’t work. Mechanic says he’s done it often, and it works.

I replaced the H11 bulb in my gal friends car once in 2020. Again in January 2021. One way of course is to reach in thru the access port in the wheel well. The other to completely remove the headlight assembly! Not (1) person to "include" mechanics has pointed out what I found 2 weeks ago as the same low beam bulb seemed to go bad "again". That is...not one person has identified the severe "crimp" that is put on the wire lead inside the "too-tight" round hole that the socket/bulb is inside of. I created a YouTube Vid - refer to: https://youtu.be/hCPwQMbRlro (copy and paste in your browser) revealing the fix! Those being told by a shop/dealership to replace the entire headlight assembly? You have to be joking! A relay? Possibly! A fuse? Possibly but unless you use an Ohm meter to check out the bulb and if good, the pigtail lead can be bought for under $9. Check that the 2 wires going IN TO the plug are not severed. Partial contact will give you a false read. It takes less than 15 minutes to pull out the headlight assembly to complete the change out of the 2 wire plug and offer assurance of a new/good set of wires going to the plug and bulb.