I think it's the low beam headlight bulb on the driver side (Whitish Light) that does not work but the other side headlights work fine. I went to longo lexus dealer and they said that it would cost 2000 dollars to fix because there is a hole or something and water gets in? I am not sure what they said, but do you think I can just replace the bulb and it will work, or do you think the dealer is not lying and he is right?

They are talking about replacing the light assembly. Does it have a hole in it? I can't speak to the dealer's integrity, you are the one speaking to him and you have the car. I haven't seen either!