How can I fix my Frigidaire classic series refrigerator?

My refrigerator stays cold for about a month and then it will start to warm up slowly. This will last for about 2 weeks or longer. The freezer stays cold. Not as cold as it should be but cold enough. Also when this started, the water line to the icemaker stopped supplying water so no more ice. The water on the door still comes through. It' a Frigidaire Classic Series side by side refrigator. What is the problem?