It seems to me, like I know anything, that an electric heater (not a
heat pump) is like a giant toaster and they would be rather simple.
Maybe there's some sort of internal breaker that's tripped, is there an
extra breaker for your heater like they have for C/A units ? Electric
heat is motor + toaster elements, maybe there's a breaker for the
toaster elements that's tripped. If not obvious, it sounds like a
service call to have someone look at it.