could it be broken fuse or wire disconnected somewhere?

Has it been impacted or struck by anything?
If not, your first place to check is the fuse box.

The car's manual will tell you what else is on the same circuit.
See if that's still working.

Could simply be the motor has burned out. If it is the motor, it's easier to replace the mirror assembly

if BOTH your mirrors aren't working, check fuse

if only 1 side is dodgy... check the various plugs along the circuit - could be corroded

occasionally the switch can get dirty or burnt

should be 2 motors per mirror usually, not often BOTH die at same time

Had this happen to me once. The little motor arm that attaches to the back of the mirror had come out. All i did was apply some pressure to the mirror and the arm popped back in

yea the actual mirror & backing plate is held in by a big ball-n-socket, then controlled by little ball-n-sockets 1 each for the 2 motors

be careful if you've got fancy glass (auto dimming or heated), they'll be wires going to it too