Windshield wiper arms usually fail due to a loose nut or rusted and worn out parts. Fixing this depends on how the wiper arm attaches to the vehicle. Fixing wiper arm failure is usually as easy as tightening a nut or replacing a worn out or rusted part.
Get in your vehicle and turn the windshield wipers on. Notice if both wipers move, fail to move at all or if one is moving slower than the other. Determine if the wiper moves a little or not at all. Some movement can indicate the nut that connects the wiper is loose while no movement at all might mean a part is actually broken or rusted.
Examine the wiper arm and its connection to the vehicle. Remove the wiper arm if necessary to examine its connection to the vehicle. Tighten any necessary parts using locking pliers or an adjustable wrench and turn the windshield wipers on again to see if that fixes the problem.
Check the condition of the wiper blades. If the wiper arms move fine but you still can't see, you may need to replace the wiper blades.
Consider taking your vehicle to a professional if tightening the nut or replacing worn out parts doesn't do the trick. They may have to replace the motor or install a new wiper arm.
Never turn on your windshield wipers in freezing weather unless you know they are free from ice. Turning on frozen windshield wipers can wear down or loosen the retaining nut, leading to windshield wiper arm failure.