Just started it up tonight and noticed highbeam was switched on (someone playing with my bike...?)... I switch it back to Low and NOTHING, lights not on. Only high works.

Is there something I'm missing?

I tried starting it, ran it for a bit... toggled various things, nothing got Low beam to come on.

Low beam's probably burnt out

It's probably the headlight low beam filament burned out.

If you have a voltmeter or 12V bulb type tester, open up the headlight housing, pull the headlight connector off and test for 12v on the white wire (ignition key switch on and headlight switch at low beam).