Need support for monitor

My monitor lately im seeing that its kinda losing its power its going dull + another wierd thing when I turn off the screen because im away studying usualy for a few moments I get that screen all kind of coulors like buncha strips and the monitor starts outputting strange sound from it which fade after a few seconds what could this be?Note monitor has been used for over 5 years now I belive could the screen be Dieng.