I am artistic and creative. There was a time that I designed counted cross-stitch. I was doing it for fun as my baby napped. It was my down-time and I enjoyed it. Later my designs were picked up by a nationally known company. At first they loved what I created and I was nominated for an industry award. After a while it got to be “design this way with these colors, etc, etc”. It got to be a chore and what I was producing was dreck. My heart was not in the design work. I was outside of the creation process and lost all enjoyment of doing it.
I think it is the same for writing. If you are writing from inside the piece.. it flows like a captivating piece of music. You are there and swept up with the complexity of the melody. Then something jars you outside…. it becomes you being the writer not you writing what is unfolding. This could happen when a discordant piece of the plot starts tearing away from the story stream or perhaps you are being told to how or what to write. It can also occur when something in your life trips you up and you temporarily lose the flow of the melody in the story.
I think the idea is to re-engage with your piece. Pick it up and start reading it with a fresh eye. Writing on a computer is terribly convenient for times like this. Save the original for the time being and make a copy of what you have written thus far. Start reading and altering, as the spirit moves you. I believe you will be drawn back into the creative flow and swept along in the emerging music of it.