I agree with NileDAngeli - but "never mind" has at least two meanings in English. In situation 1, "never mind" = "cela ne fait rien," and in situation 2, "never mind" = "laisse tomber":
(1) Peter: I'm sorry, I accidentally broke your window. Paul: Never mind. (Or, that's okay)
(2) Peter: I really think that cubism is the new impressionism because of the study of perspectives, blah blah blah, Paul: What? Peter: It means that they both share a certain je ne sais quoi. Paul: What? I don't understand you. Peter: Oh, never mind.