A stuck brake disc is usually a sign that the caliper has frozen with the piston in the extended position. The fix for this is relatively easy. You will need to jack the vehicle up at the problem corner and remove the wheel. On top of the caliper is what is known as a bleeder screw, which you will need to loosen, but not remove. About ¾ of a turn is all you should need. Take two large screwdrivers and carefully pry the caliper away from the rotor. Once you have the caliper loose, you will need to remove it and determine why it became stuck.
For more info, see How to Tell if a Brake Caliper is Bad