Personally I don't believe in writer's block. I am sure that if you went with pen and paper (or whatever you normally use) sat down and wrote you would be perfectly able to. We just tend to get occupied with other things and our minds will up with thoughts that hinder our creativity.

The thing though, is that we can not always write what we would like to write, say for instance finishing a piece.  Which normally means; that the start, middle or ending of a piece is not right within our heads, and so the best thing to do is to plan it, even or re-plan it, until you know what you have to write.

If planning or re-planning doesn't work try some activities, such as writing ‘what happened to you today’, or ‘what you would like to do tomorrow’. Anything silly works too. Sometimes when we start to write are mind gets into gear and then we can start or work on what we wanted to write.

What I used to do, which may seem or is listen to a piece of music depending on what scene I intended to write, it requires quite an extensive selection of music from many genres but if it help it is worth it. All you need is a little motivation to get into the swing of things again.