If your power mirrors have stopped working, it's likely because of a problem with the fuse or wiring. To check the fuse, first locate the fuse box - usually under the dash or in the glove compartment. Once you've found the fuse box, look for a label that indicates which fuse controls the mirrors. If there is no label, consult your vehicle's owner's manual to be sure.
Once you've located the correct fuse, remove it and inspect it for any signs of damage. If the fuse looks damaged or blown, replace it with a new one of the same amperage. If replacing the fuse doesn't solve the problem, then there may be an issue with the mirror's wiring.
To check for problems with the wiring, first disconnect the mirror from its power source. Then use a multimeter to test for continuity between each wire terminal and ground. If there is no continuity, this indicates a break in the wire and will need to be repaired or replaced.