A group of students perform a scientific experiment in which there data disproves their hypothesis. Is the data collected still available?

Yes, data is still available. This is because in the scientific method what determines the outcome of the investigation is not the previous hypothesis, but the verified data. In other words, what is tangible is the data that offers a real result to the investigation; the hyphotesis is a mere theoretical approximation to the future result that the data will offer.

Even the currently data at the moment of the research refuse the presented hypothesis, we must take into account that said data will keep available, and it will be probably the answer to another questions and the base for other hypothesis, we must not forget the scientific method always is searching the explanation of the phenomena surrounding us.