Barcode halfview

This would be my first time reaching out to ones , who may know right off to issues , I've only began learning basics about my computer a year ago , my screen, coming from a latitude D830 one day just blacks out, no warning shot, eventually mysteriously it comes back , however on the top half of the screen has a normal view and then the middle through the bottom is barcode looking lines running from left and right, with pure luck in guessing , you can click on things down in the abyss , an external monitor does work and can operate it that way, but it's quite a pain, backstory real short , this laptop has been with me , through Iraq 07-09, and afghan 10-11, exposed to sand extreme heat , extreme cold , without even the cooling fan working ( I've never heard it work since owning it.  So I have a bit of an attachment to it and only running windows 7 home on it ( doesn't want to upgrade to windows ten, stubborn s.o.b) , it seems like it could be a quick easy answer , but I'm frazzled for over a year , lack of money consistently prevents normal replace fixes, but it'd be nice to know where to start , anyone please , if ya have a more likely to be cause and solution I'd appreciate it, TY