A lot of writers like using the older AlphaSmart keyboards because they don't allow you any editing function except a backspace key. You can't delete or highlight to cut and paste and shift text around.
This is great because when you write, you're focused on creating text, not agonizing over word choice, sentence construction, and whether this paragraph goes here or better there. You just write and move on.
There are many successful authors who have taught themselves to just get the first draft done by whatever means necessary. They write and keep writing rather than backtrack or constantly edit the same pages over and over. That way, they get it down, then they can go back and edit and polish.
If you're stuck in your writing, maybe you just need to write hell bent for leather and just keep moving until you type The End. One way to do this is with a hardware device like my old AlphaSmart. The other way is with a software application that blocks all editing distractions. Here are 3 for you to sample.
Write Or Die
You can use this free online or download it for a paltry 10 bucks. You set a word goal and/or a time goal, a Consequences mode from Gentle to Electric Shock, and a Grace Period from Forgiving to Evil. Click Write and get started. I've used this. You cut and paste your work from the screen to your word processing app when you finish.
When you click Done, you get a screen with the purchase link. The purchased version has Kamikaze mode which I like. Yep. I bought it and think it's a great tool.
This a free Windows download that also creates a distraction free writing zone. The icons you see in the upper right corner are there only when the mouse is passed over them and govern the functions to create a new document, save your document, and make minor changes like increasing or decreasing the font size for your convenience. You can save your work as a TXT, RTF, and DOC, and the files are compatible with nearly every word processor if you want to import your text for later editing.
Writemonkey is another free software, though you can donate via PayPal if you like it and want to support it. If you donate, you'll get a file that will enable personalization, and you can access hidden features. This is another software app that seeks to eliminate distractions therefore it's a text editor with minimal editing functions. It's designed to take over your full screen and won't allow you to open another window without exiting.
If focusing on your writing, and ignoring distractions, is a problem, then try one of these solutions.