Horizontal line in the middle of the television. I have a Magnavox 27 inch television set with

Question

I have a Magnavox 27 inch television set with just a horizontal line in the middle when turned on. The sound and even the channel changer works. I would like to know if this is a costly repair, or is there something that I could do to fix this?my SONY TRINITRON / MODEL 32S22 I can hear and chage chanel but I cant see the picture