Depending on year, the light switch is incorporated in the door latches.
They tend to stick, which leaves the interior lights and you going crazy
trying to figure out why.

I sprayed my locks with brake parts cleaner to get the original grease out
(make sure to protect the paint from overspray), and then lubed with
silicone spray.  No further problems in 6 yrs.

Has the rotary type dimmer switch on the dash accidentally 'clicked' into
the on position? Daft as it seems, this one had be baffled for a couple of
days...

Simon H