If it is not a problem with the screen it could be an issue with the software that talks to the screen (the driver software). When you boot it up is the blurriness there on start up? If not then good news is the software is the issue! You could then go into safe mode and do a “system restore” using the windows application.
My Video Is Blurry On My Screen What Should I DoAttach a different screen. If it is a laptop it might have a “VGA” output on the side of it where you could insert it. For a desktop look for where the current screen is plugged into. Still blurry? Not a problem with the screen! Not blurry? Issue could be with the screen old screen.