No picture, only sharp, squeaky noise

Question

Hi, Our computer was working perfectly fine until this morning. I turned it off because I left the house for about an hour.When I returned I tried to turned the TV on but no picture came on only a sharp, squeaky noise that stays on. I can't even use the TV button to turn it off. I had to unplug the TV because of the noise. Please give me some advise. Also, do you have any idea how much it would cost to get it fix? Thank you Otilia Green