How can I find the changes I have made?

I have received a maintenance change request on one of the program. While I am making changes to the program, one of my friend came to me and  We leave for a cup of coffee without SAVING the changes I made. After few minutes , when I am back, I am not sure what changes I made previously on the program? How can I find the changes I have made (without getting out of this screen)?

Well, here is one simple command line command to achieve this.


COMP * X