2009 accent headlights won't turn on

take the bulbs from the other assemble and put it in the new to see if it works then.

or check the low beam fuse in under the hood .

Since you just messed with your lights I'd look over the connections carefully and check your fuses to see if you accidentally shorted something (if the lights were on at any time when you were changing out the lights). There is a (nearly) hidden relay for the headlights up under the dash and I have an article that shows you the type and location of that relay: http://www.shareyourrepair.com/2016/03/hyundai-accent-headlights- will-not-come-on.html

what am i that stupid or is this site a bunch of jerks you have my problem listed no headlights on 2009 hyundia accent jon fixesstuff say almost hidden relay under dash but stops there n wont tell you where i suppose this is one of those sites that draws you in then wants a fortune to tell you its people like you that give the intr a bad name if its me not doing something wrong im sorry but i dont think so im so sick of this crap im 62 yrs old n this is the first time i have ever sent a complaint but u no what i think people like u suck thanks for wasting my time jerks