That's a strange file type for a data file, .CNT typically is a content file for the MS Windows help system. Have you tried to look at the file in a text editor. If the content makes sense (e.g. data delimited by tabs or similar) then you can try to change the suffix to .txt. Text files can be imported into jmp. If you first need to rearrange data, you can to that either in the text editor or import into Excel.