Beat the edge of the stud with a hammer to attempt to turn the stud. This is the easiest method and can work if your stud is just slightly out of alignment with the rest of the wall studs. It may take several minutes of hammering against the edge to get the stud to turn completely, and you will need to use significant physical force, but it is the most basic way of turning a stud on a load bearing wall.
Turn the stud with leverage. Clamp a crescent wrench over the stud. Grasp the wrench firmly in both hands and put the weight of your body behind it as you attempt to pull or push the stud to turn it. Failing that, place a length of hollow pipe over the handle of the wrench and use that to apply some extra leverage. Apply pressure slowly and only turn the stud as much as is necessary.
Take some of the load off the joists above the studs with an adjustable jack post. Insert the jack post into the wall alongside the stud you need to turn. Unscrew the jack until it is tight against the floor joist and the ceiling joist to which the stud is attached. Jack the ceiling joist up slightly so that the pressure on the wall stud is relieved and use one of your turning methods to turn the stud. Release the pressure on the jack when you are done.