If a vehicle with power steering suddenly becomes hard to turn, it is typically a sign that it doesn't have enough power steering fluid. If there is enough fluid or the issue persists after adding more, it may be necessary to have a mechanic inspect the steering column for problems.
It is necessary for the vehicle to be warm when checking the power steering fluid, so either check it after driving or start the vehicle and let it idle for a few minutes. The vehicle should also be parked on a flat surface.
When the vehicle is warm, turn the steering wheel each direction as far as it goes a few times. Then pop the hood and look for the power steering reservoir, which is usually near the engine. Depending on the type of vehicle, the fluid is either checked using a dipstick or by looking at the markings on the side of the reservoir.
If the level is low, add enough power steering fluid to fill the reservoir. Make sure to use the specific type of fluid recommended in the owner's manual. After filling the reservoir, check the hoses and seals around the reservoir for leaks to prevent the problem from reoccurring.