When you say that the heater no longer works, do you mean that no heat comes
out of the vents, or that the blower doesn't.
Assuming the latter, the fan is under and behind the glove compartment on
the passenger side. You can easily remove it after removing the glove
compartment.
However, you don't say if you have climate control or A/C, as this increases
the complexity of the control system, which could also be at fault.