Tickets are usually non-refundable. Most tickets are non-refundable, so you probably won't get your money back. If you are a subscriber, you might be able to exchange your ticket for another time. Call the box office to check their policy. Ticket prices vary from zero to more than a hundred dollars.
Large theaters have more than one ticket price.
In general, the seats get cheaper as they get farther from the stage. In some concert halls, the cheapest seats are the best place to listen, because the music floats beautifully up to the top balconies. Concert brochures and advertisements often list ticket prices, or they'll give a number to call for more information. Usually when you buy a ticket to a classical music concert, you buy a specific seat. Your ticket says where you will sit.