the main brake lights do not work could it be a blown fuse?

Because they both went out at the same time I would say that it very possibly could be a blown fuse. Check the fuse box. It should be located somewhere to the lower left of the steering column (thats where it is on most cars.) The fuses are numbered and there should be a diagram of which fuse belongs to which component located either on the face of the panel, or in your owners manual. Try replacing the approprite fuse and check to see if the lights work. If not it could be a wiring malfuction which is infinitely harder to replace.