Tough Christian question?

I'm a believer but I can't seem to get this question out of my head. When Jesus was on Earth, He healed the sick and the blind and performed many miracles. But why doesn't stuff like that happen now that He is in Heaven? For example lets say a man is blind. He's a believer and prays to God to heal Him from his blindness much like the people in the Bible who were also blind. But he doesn't, nothing happens. An example like that among other things. your answers would be appreciated.