Head lights

Ok so this is what we know.

1.The high beam work.
2.That means there is power to the high low switch.
3.There is power out of the high side of the high low switch
4.The ground to the headlight bulbs is good.

Assumptions

1. The high low switch was replaced because the low beam were not working and it did not fix the problem
2. Liklyhood of 2 switches being bad in the same way small

What we don't know

1. Is there power out of the high low switch on the low side
2. Was any wiring changed.
3. Is there power at the head light bulb socket on the low beam
4.are the connectors at the high low switch making contact.
5.has the OP traced out the wire for the low beam from the bulb socket to the high low switch, looking for broken wires

An example of a wiring change that would allow high beam to work but not low beam would be if the feed to the high low switch was switched for the high beam output.

The high beam would work but the low would not.