It is hard to know how to advise you without knowing anything about you and what you have tired, if you are young/old or have you been treated for any kind of depression. However without knowing anything the one thing that might work is to stay busy with life. Volunteer work, if you don't have an animal get one ...just whatever you have to push yourself to do. Don't stay isolated you really have to push yourself. And if you can afford go to the doctor go. Good luck.
Well if you know whats making you sad, you need to find a way of overcoming it. Otherwise you need to keep yourself active one way or another. Give yourself a few goals to achieve that are challenging and that you enjoy, for example you might enjoy succeeding in completing your plans which is tricky to organise but if it works out, it can be rewarding. Let me know what you think. Thanks