Amro, I had to clean a keyboard for a friend once, if cleaning through the other mentioned options, the next step, if feeling confident enough, is to lift off each key individually. they usually pop off if you lift the bottom edge. They hinge up in some cases and a cotton bud can be used to clean underneath. In some case there is a rubber cup, this too can be lifted off and cleaned with some warm water and dried totally before replacing. Again the area where it sits can be cleaned with a cotton bud to remove any sticky residue. The key then can be placed into position and pressed firmly down replacing it into its place. Hope this is of help. Mike