My car is a 99 Civic EX. I don't understand why but left side headlight(corner bulb's fine) dont work even though I'm running PIAA bulbs with stock watts, 60/55. Does it mean I need to get replacement bulbs even if my high beam works for both sides? Is there a loose connection somewhere? Any help will be appreciated. Thanks a lot

sounds like the bulb is cashed.
disconnect & remove the bulb
reconnect bulb out of headlight assy.
move & twist the wires/bulb around - if the light comes on, you have a wiring problem.
Never touch the glass parts with your fingers

Also the lowbeam filament of the bulb could have blown out, I had that happen with a set of bulbs once (higher wattage ones though) where the lowbeam of one blew out, but it still worked for high beam. Send it back to PIAA, I think they have a good warranty on theirs...