You need to find the cause of the trigger. If you can't think of any thing that triggered this then you have to look at yourself and ask what has happened. What made you be great and happy to be depressed. If you find the trigger to actually be something then it would be easier for us to help you, even if you don't want to talk about, talking about will help and make it easier for us to help. If you are scared or embarrassed I understand but we are mere stranger who don't know you.