Okay, so I only have one published eBook out there, and I've only been seriously writing for two years. So what makes me an expert? Trust me, I'm not. This is just my personal opinion. I think most writers who believe in writers block do so because they have this preconceived notion that there is such a thing. I don't believe in writers block. If writers who stumble on their stories don't immediately think "Oh, no! Writers block!” then the mind wouldn't freeze up at the thought.
I believe when you hit a dead end or what you might call "writers block" your content-mind is trying to tell you, "Hey look, were done." End that chapter and start the next, keep it rolling. If you can’t let it go, then you need to listen to the sleeping part of your mind (the subconscious), or your unaware mind, aka your "muse".
What is that? The subconscious mind is where all your thoughts and ideas are stored when your conscious mind is not using them. It's kind of like your own personal file cabinet.
How do you unlock it or open it? Well, it's different for everyone, but when I lie in my bed and relax, and try to NOT think about my story, that's when it happens! If you don't know what works for you then the next time you hit a wall, go lie in a darkened room and relax. Not just your mind, but your body. Start at the top. Think about each body part as you relax them. Start with your scalp, then your face, your neck... and so on. If you do this and take it seriously, you just might fall asleep! (This sometimes works at night when I'm restless). When you finally get down to your toes to relax them, slowly introduce your story to your mind. Then see where it goes.
When you don't have paper/pen or computer nearby the ideas just seem to roll in. Some other approaches you could try: going for a walk, a jog, or go shopping. All the while think about your story. Don't obsess over it, or it will do you no good. Just casually have an inner conversation. No, not with yourself silly, with your characters! Cuz' talking to yourself is just plain crazy! :)