new left headlight not working

The first thing you have to establish is whether there's power at the connector. I'm guessing no because the problem is only in one side. Once you establish that there's no power, you have to chase the power chain back to find the problem. It could be as simple as corrosion at the connector. If you aren't comfortable working with voltage get a pro to look it over because you can get a nasty kick here. Good luck!

there is not much of a kick from 12 volts. ( none ) the wiring stats on passenger side and crosses to drivers side in front of radiator that line corrodes and breaks near to center or to right of center, you can do this yourself if you can do other things like oil change or replace battery. it is easy, just a knife and wire about a foot, and black tape you may have to remove plastic shroud on top of radiator or hood latch. have fun..

you would pretty much have to lick both of the battery terminals at once to get anything and it wouldn't be much more than a tingle lol lick a 9V toy battery its something like that