First question is if it oem fog light or aftermarket from ebay or something? 2nd, how long have you been having it and when did the light bulb went out? So you brought 2 new bulb and only 1 work and the other not? Try the working one on the side that does not work and also try the not working bulb on the working side to see if it the wiring or bulb itself that doesnt work.
Once you got conclusion on those, post it up to see if you need more help from that point on.
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