I haven't been able to write for a very long time, is it a writer's block? And how can I deal with it?

By relaxing and gathering some new ideas, and the most importent thing is to have faith in your self and capabilities as a writer so you could injoy what you do .  

Writer's block heals itself when your mind is relaxed; try to take your focus off the process and think more of other things because that is how inspiration comes. Not being able to write also means that you have too many ideas and can't pick between them so brainstorming is another way of fixing it.