Studying in Ireland, I want to travel to France and Italy, but my visa is refused. What should I do?

Apply for a Schengen visa in any country's embassy for a long time, otherwise it will be a disaster. You can try to lodge a complaint, but my experience in France for many years shows that the effect is not high. You can also consult the Italian Embassy for remedial measures.

Remember to study relevant policies and regulations in advance in the future, apply for a visa first, and then buy a plane ticket. There are plenty of cheap air tickets in Europe, so you don't have to buy them in advance.