There really is no such thing as a painless and foolproof method. It just doesn't exist. Believe me. I've searched. The thing is humans are animals, and our bodies are designed to fight for life like any other creature of nature. Despite what you see in the movies, people are hard to kill. We've evolved to hold on to life and that is what our bodies do, and there is no painless or failproof method. The vast majority of suicide attempts fail and they can leave you in even worse shape than before. I'm reading a book about a kid who wanted to die so badly he did something catastrophic to himself, but failed to die- months and years of surgeries, pain, etc. You can be left with brain damage or with organ damage, or on dialysis for the rest of your life, or paralyzed. No perfect method exists.
Are you sure you are going to feel this way forever? I know for me, when I'm in a depressed state, it always feels like forever, but it never is. Have you ever been happy in the past? What made you happy then, and is there any way to replicate or recapture that now? And if not now maybe someday in the future?
This isn't a place to trade suicide methods - this is a forum where we come together and help each other to stay alive. No one here will help you kill yourself- but please don't leave. Maybe someone has an idea that can help you. All of us here have dealt with depression and suicidal feelings, and many of us have attempted, but right now we're all still here and we're all trying.
Do you want to share some of the things that may be bothering you?