You're going to have to do some diagnostics work here I'm afraid. When you say the application has stopped working, does that mean that it doesn't start up, or that it starts, runs for a while and then stops? The first two things I would do are:
- Look into the event viewer to see if your application has crashed and written information to the event log.
- Make sure I have exception handlers to catch unhandled exceptions, and add logging into the application to log what is happening.