Screen gone out. I have a philips magnavox. I've had it for about 6 years. The screen recwently

Question

I have a philips magnavox. I've had it for about 6 years. The screen recwently went black. I have access to sound it's just the screen. it's completely black. The channel numbers don't even show up and when I switch imput I can here the games or dvd's on but no picture. This first happened a vouple of weeks ago But I tried rectifying it by hitting the side of tv. This brought the screen back. I didn't have to tdo that for a while and then I had to do it every time I turned the tv on and now hitting it doesnt even work. What should I do?