I ran into that several times while rewiring. It was always the plug connection at the firewall with the plug that the tail lights go to. They can come loose while working, or if it's not snug, the brake lights won't come on. To check mine by myself I wedged a stick against the brake pedal and the seat to depress the brakes. I don't think it would be the bulbs because it's unlikely, although not impossible, for both to go out at the same time. If it's not the plug then check the brake pedal to make sure it is engaging the brake light switch when depressed. If you did any work under there while wiring you might have knocked the connection loose. Hope this helps.
