Be it an 5000-word essay or 200-word formal email, no one is immune to writer's block. Fortunately, there are a few techniques you can try to jolt your brain back into action and coax more words from whichever mental crevasse they happen to be lodged in.
An article over at HackCollege covers six tips that can potentially save your typing bacon. Sure, you can try going for a walk or taking a short break, but one that might not seem immediately obvious is keep writing... about something else:
Write -- But Not About Your Intended Topic When you get back to your computer, write about how you feel. Write about what you want to do. Write about how annoyed you are that you can't write this thing you need to be writing. Write about how much fun you had when you weren't writing. Now you’re getting your brain warmed up for the task at hand.
My own piece of advice is to just start in the middle. It doesn't matter if it's the second paragraph in a three-paragraph missive, by going straight to the meat of the document, you'll find your brain automatically focuses on the most important points you need to cover off. Once that's done, it's much easier to formulate an introduction and conclusion.
6 Ways To Overcome Writer's Block [HackCollege]