In R32s, I've found the 'one head light' problem is almost always the headlight cabin switch. The switch has 3 springs, one for the right headlight (highbeam and normal), same for the left, and one for both parkers. The spring tends to sag and looses it's elasticity so it's possible to loose a headlight (normal and highbeam not working at the same time, on one side). Because the spring has sagged, it can't complete the electrical connection (yes 12v runs into the cabin, into the said switch) where it would normally push a tiny metal plate into the other when working properly, to complete the connection.