Depending on your triggers, this question is one that many people struggle to answer.
The one thing I know from struggling with my own battles, my depression comes and goes.
Bipolar depression is something that I relate to more although I have never had a formal diagnosis of anything outside of when I was 16.
However, as hard as this is going to be, get some help. You don’t have to go to therapy, or get medicine if you don’t want to, just find that one thing that brings back that piece of happiness. Then run with it, train yourself to engage in one thing a day that brings you joy. This is easier said than done, it takes a lot fucked up feelings to get there, but you can get there because you’ve already come this far. Why stop now? Find your happiness and don’t let anybody stop you on your journey!
As always, reach out if you need someone to talk to.