The most important thing when it comes to debugging your program, regardless of programming language or platform, is to know which part of your code is causing the problem. There are several ways you can identify your problematic code:

Ask the user at which point the bug happened; for example, which button was pressed, what were the steps leading to the crash, and so on.
Comment away part of your code, then build and run the program again to check whether the problem still occurs or not. If it still does, continue to comment out more code until you find the problematic line of code.
Use the built-in debugger to check for the variable changes within your targeted function by setting a data breakpoint. You can easily spot if one of your variables has changed to an unexpected value or an object pointer has become an undefined pointer.
Make sure all the libraries that you included in the installer for your users have matching version numbers with the ones used in your project.