There is nothing worse than when you want to write and those words just won't come. For some, it's a mild inconvenience. For others, it causes sleepless nights and all-around annoyance.
Unfortunately, there aren't many quick fixes. Sometimes, you just have to ride it out and wait until the brain fog clears.
However, one thing that has been super useful to lots of writers is the use of prompts. If you're struggling with your own book, taking a step out of it and writing something different is a good way to shift your focus. Not just a different story, but how about trying a different genre too, just for a piece of short fiction?
If you are having a hard time focusing on your own story, try one of these:
You wake up in your own bedroom, but instead of your usual decor, the walls and ceiling are now covered with mirrors.
Write about a character who is finding it hard to let go of something.
Write a story that begins with the words "You are a liar!"
You get on a bus, but instead of taking its usual route, it takes you and its other passengers flying past their destinations.
Try to think outside the box a little if you can. For example, for a character struggling to let go, for some, the obvious choice might be that they are trying to let go of a person or situation. What if they are struggling to let go of something physical? What is it? Why are they struggling? Just let your brain have a total workout, and feel free to comment with anything you come up with because I would love to see!