Main lights

Hi I have a Landrover series 3 and was wondering if anyone had theory’s why my side lights and high beam work ok and my main lights have stopped working? The high beam works from my indicator stork so the light switch is a 3 way switch off side lights on and main light, I’ve tried changing the switch new lightbulbs but no joy and checked what fuses I have but still no joy bummer I’m good with mechanics but not with electrics plus I have lots of wires that lead to nowhere? Iv even tried looking for the earth points but it just looks like a big plate of spaghetti Thanks Andy