You need to drop the front bumper. This is quite involved, from memory 2
large bolts on the topside, couple on each side, in the fender (need to
remove plastic wheel arch liners) and about a dozen small bolts on the
underside, that hold the plastic cover that is under the engine. Then 3 more
bolts to remove each light. Oh and be very careful not to break the adjuster
tabs when putting new bulbs in. The clip is fiddly but can be done without
all this dicking around. Get a small mirror such as that used for dental
work, and a flashlight, and see what the problem is. The fiddly little bits
they put on cars can drive you insane.