This may look like a contradiction but a writer's block mostly happens when you don't like it anymore, the interest of "writing". Also NOISLI can be a good solution. It is actually an app to help their users "focus" better ; but they also have a "distraction free" text editor with the ambient sound you wish in the background. You can find "NOISLI" and many others from here..: https://steemit.com/steemit/@lamegliogioventu/best-online-services-and-tools-a-library-for-the-most-useful-online-services-and-tools