Trouble with keys not working

[tbaby504]

i have a acer exstensa 5420 and the keys, sdghm and the upper arrow is not working...i have cleaned them but still, they dont work. how can i fix this?

 

[Maxx_Power]

i have a acer exstensa 5420 and the keys, sdghm and the upper arrow is not working...i have cleaned them but still, they dont work. how can i fix this?

Unless you want to take apart the keyboard and see what's wrong inside with either the membrane or contacts or electrical traces, the only thing you can do is to try to find a replacement keyboard on eBay if you are out of warranty.