A bad brake light switch or a bad headlight switch, or the power source of the fuse has a problem or break in the wire (circuit).
Is the light bulb inside burnt out. If so, that would do it.
If the bulb will not work the fuses under the dash should be checked. When these fuse fail the brake lights will not turn on.
Check all the fuses and replace all of the blown fuses. If you still have no brake lights check your brake light switch. The brake light circuit also runs through a red cylindrical shaped relay called the "failure sensor" which lights and indicator bulb in the intrument cluster if a brake light bulb or some other bulb has failed. Internal failure in this part will often have the symptom "No brake lights".
A blown bulb. Check fuses and then start replacing the bulbs one by one.
Try to find out if the car have fuses for left and right brake lights. And did you replace the bulb on the side that is not working?
Usually through the back panel in the trunk
First check if bulbs and fuses are good and see if the back lights come on when you turn on the lights. If everything works and the bulbs and fuses are good then its most likely the brake switch on your brake pedal, its usually the only thing wired to the brake pedal. If its not that you might have a short somewhere but usually its either fuses or the brake switch, both are cheap and easy to change.
there are under the brake pedal a switch which control brakes ligths . You may check the swich after checking fuses,and bulb.
Have you checked your bulbs ? The tail light / brake light bulb has 2 wires inside it In my case I have had to change each bulb because the brake light portion did not work but the tail light portion of the bulb did ( I'm assuming that your front park lights are working )
Something you may not realise is that the brake light bulb is often one bulb with two elements. One of the elements will be for the brake and the other will be for the tail lighting for example so,when tested, the actual bulb will still light up because the second element is unaffected. Make sure that the 'blown' bulb that you are actually changing is not in fact your fog lamp. This will not automatically light up when you test your lights as you have to operate this light separately (similarly to indicator lights). So the fog lamp bulb will appear to be the only one not lit up when you test your lights. Find the bulb with two elements inside and change that one. Sounds obvious (and may be obvious to many) but it's a common mistake. Hope this helps!.
if the plug is receiving power but the lights wonbt come on you may have to replace the entire lens piece since the brake lights are not a normal bulb they are built into the lens
It can if it is a dual filament bulb as found on most US. makes. The brake light filament can short over to the tail light filament inside the bulb and when the brakes light is activated, all the tail lights and front marker lights will light also, probably blowing fuses.