Sounds like you've lost power to the boot solenoid.
When mine did this, after a couple of days or so I'd lost all lighting relating to the boot - ie numberplates, rear fogs etc.
It's a common fault ironically caused by opening and closing your boot.
There's a bank of wires that sit within a plastic protection tube which is strapped to the left hand hinge. Wires within here fray over time and eventually break.
You need to strip the protective covering off, locate the broken wire and reconnect it.
In my case it was the earth wire and I lost the lot.