I had a 2 problems in my acer laptop
1 is down arrow key is not working
2 is in display it had lighting small small patches how cai i remove from display
This can be frustrating, but sometime physical thngs just break. As far as the keyboard, turn off the pc/laptop and get a can of comprressed air and blow out all of the crumbs stuck in the keyboard.
As far as screen "artifacts", once again, no amount of tweaking can repair a physical problem, and if you have the same aritfact in the same corner of any screen, then more than likely is a pysical problem.
Let me know if yu beleive it is not a phyical thing, let me know the model number and I will help.