Answer:
I build up castles. I tear down mountains. I make some men blind. I help others to see.
I can be used to type and point you see. But don't forget, you can count on me. What am I?
I'm sometimes white and always wrong. I can break a heart and hurt the strong. I can build love or tear it down. I can make a smile or bring a frown.
The more holes you cover the lower it goes.
Break it and it is better, immediately set and harder to break again.
I appear in the morning. But am always there. You can never see me. Though I am everywhere. By night I am gone, though I sometimes never was. Nothing can defeat me. But I am easily gone.