Let me explain my definition of miracle. For me, a miracle is an event which is not predictable or reproducible by the natural causes operating at the time and place the event occurs. The virgin birth is a miracle. Jesus' healing of a blind man by rubbing mud in his eyes is a miracle. But my definition would NOT include something like chemotherapy curing you of cancer.
Chemotherapy is rightly in the realm of science.
Science cannot prove or disprove miracles because the goal of science is to seek natural explanations, i.e., to study cause and effect in the natural world. Miracles, by definition, originate outside of nature, outside science's field of study because they don't deal with natural law. For a scientist to claim to be able to disprove miracles would be like a doctor proposing advanced theorems of quantum physics. It's outside his field of study. We now know, for example, thanks to Dr. Edwin Hubble, that the universe is expanding, and that it began with an infinitely dense mass of matter that somehow exploded about 15-20 billion years ago.