How can i fix my Magnavox PTV630-AH01 ?

my magnavox ptv630-ah01 has a black screen with a white line down the middle. sometimes it will play for two or three day and then ill cut it off .but when i turned it back on its black again with the line and i can hear a buzzing sound in the back. sometimes if i tap the right side i get a picture. i would like to fix it so please if someone knows whats wrong with it or how i can fix it please tell me . Thank you