Not responding app or program is a common error in windows pc, but sometime it will create serious situation, sometime it will happen in bad situation like preparing data or working any program, if you got not responding error, than you have only two ways, wait for few moment to resolve itself or do the end task, but doing end task may be lost some of data.. (so do this on your risk).
1. When you got this type of situation hold “Ctrl+Alt” key and press “Delete” button select the “Task Manager”
2. Select which program or app is not responding and click on “End task” it will close the program without distributing other stuff