There's a myth of the empty page. You want to be creative, but you sit there and can't think of anything. This is most frequently referred to as Writer's Block, though it will affect anyone who creates. Also, it's a lie. There's no such thing as Writer's Block.
And yet, there's probably someone reading this article right now who disagrees. This person, perhaps it's you, is struggling with the blinky cursor in the word processing program and huge fields of empty space around it. No words are coming out. There is just nothing to write. Nothing. To. Write.
If this is you, you're probably a little bit angry right now. "Stupid Awesomeographer," you might think, "clearly he's never had to struggle to come up with words. He just sits back and writes and things happen." If this is you, and you think I'm a jerk, then do something about it. Go to your word processor and write down why I'm wrong. Make a little fiction about setting me on fire and how satisfying it is to show me who's boss. Feed me a freshly baked loaf of bread and modify the universe so that I'm gluten intolerant or something. Go on, do it, I'll wait.
Could you manage? Could you take an exercise unrelated to what you were trying to accomplish, and get some words down? If so, then why could you manage that but not whatever it is you were trying to write before?
There are a number of theories for what's going on with Writer's Block. The most popular one I've seen recently is that it's fear. Your ancestral brain, your lizard brain, your hindbrain, is trying to keep you from making a fool of yourself. Because whatever you want to do is important to you, the best way to avoid the feeling of failure is to avoid doing it at all.
There are other theories. You might be out of practice writing. You might not have given your concept enough unconscious thinking time to flesh out enough details behind the scenes. Your "writing goblins" for that style of writing might be on vacation. Whatever. Pick a metaphor and go with it for now. Work that into a routine, and see how you can use it to work around whatever your block is. If your metaphor doesn't help you to work around it, find another one.
If you could write a stupid story about me being eaten by bears because I couldn't finish a novella, thus releasing myself from the deathtrap cave, before the bears awoke from hibernation, then it's not that you can't write. It's that you couldn't write whatever you were trying to write before. Now that you've written a poem about me winning the Chicago Marathon and having a post-marathon party with Peter Sagal catered by Rick Bayless (not all the stories have to be mean), try shifting back to your original project. Often, just getting words on the page will get you past the point of not writing.
If that's not enough, there are other techniques. We'll have more articles at Awesomeography to help you with specific situations. For now, try to figure out what it is, specifically, that's stopping your from writing the thing you're not writing, and do whatever it takes to get past that. It's not that you can't create, because you can.
There is no Writer's Block, but there are little things that stand in your way. It's not monolithic. It's not something that you have to wait until it passes. It's just something you step around and keep going.