I have a single brake light that came on and won't go out now all my lights both exterior and interior won't come on except for the one brake light also my power windows, door locks and moon roof don't work

We can’t fathom what this may be - it doesn’t make any sense.. Firstly we need to know WHICH brake light is the only one turning on - is it a warning indicator in the dash OR one of the rear brake lights? You say none of the exterior lights work - not even the HEADLIGHTS ?