Anyone that writes for a living, whether it be fiction, journalism, etc. will eventually fall prey to writer's block. It's the debilitating state of mind where nothing comes together. We can sit at a blank page for hours and hours and not be able to write a word.
I remember a time when I had the idea fleshed out in my head, but every time I went to write something it never felt write. The rhythm was wrong. The wording was wrong. There was always something about that just didn't click.
This tends to happen on pieces that you spend a lot of time on such as a book or story that you obsess about. Your mind wraps itself around it so much that it shuts down. It's like running a car engine without any oil. The engine is going to run and run until it can't go anymore and jams up.
When you're hit with writer's block, the best thing to do is take a break for a while. Go outside, prepare a meal or work on a completely different story. This helps to unwind your mind and lubricate your engine. If you take the time for a break, then odds are you'll be back in the flow before you know it.
If not, then you can spend hours, days, weeks or even months stuck in a literary funk. Writer's block will eventually go away on its own, but taking a break can help it move along much faster.