I have a plasma tv need help. i have a magnavox 42 inch model # 42mf230a/37 suddenly i have a 6

Question

i have a magnavox 42 inch model # 42mf230a/37 suddenly i have a 6 inch black line running from top to bottom almost in the center of the screen.you can still see the picture on either side of the line but everything behiind the black line is blacked out.. do you know what this is and about how expensive the repair could be