Writer's block can be one of the most frustrating experiences in the human condition. There's a pressing need to write something, but you're coming up empty on what to say.
For me, writer's block generally manifests itself in one of two ways:
There are probably other, more subtle ways to describe it too. Either way, you sit and stare at a screen, writing and erasing. (Or if you're a little more old-fashioned, the cliched wads of crumpled up tablet paper litter your work area.) You feel like you may never get out of the slump.
I've been there, and still end up there relatively often. Creativity is a not a straight line. It dips and ebbs based on a lot of external factors. Sometimes we hear something that spurs us to invent a story. Other times, we're stressed about other things and can't get our minds into creative mode.
If you have come here looking for a magic cure for the dreaded block, there is none. But there are ways to work around it. One constant I have found is that if you keep writing, anything at all, you'll find your way again. I know that's advice that's often repeated, but for good reason.
For the first type of block that I personally suffer from, lack of ideas, I usually dip into the well of my memories and just write about something I remember, particularly things I find or found amusing. That was the genesis of my "Randos" blog. I needed to get away from a project because I wasn't being creative in it anymore. The ideas seemed terrible. I needed to do something completely different.
It's worked with varying degrees of success, but I find that I at least feel like I have accomplished something in writing something. Doing the deed itself keeps you in practice, the next idea is almost always just around the corner. Plus, Randos gives me a dumping ground for ideas that can't really be full-blown stories. It allows me to file away those things and clear my mind for the great stuff.
The more troubling block for most people is the second kind, where you are writing and all of the sudden the story starts to develop a mind of its own. You're writing, but it isn't what you want, and you're not sure why.
It's actually easier for me to get out of this kind of block, because the cause is almost always the same: I started in the wrong place in the story.
When you start in the wrong place (either at the beginning or laying out a scene in a larger story), you almost always find yourself in the position of having to set up too much background or you need to jump over large swaths of time to reach the next place.
This is when the writing spirals out of your control. The elements you're trying to add are likely necessary, but probably not in the way that you're trying to do it. Now you have several paragraphs that you hate or you know are flat-out terrible. Walking away doesn't seem to help.
Many people struggle at this point, including myself at times, because it is painful as a writer to scrap something you have already written in favor of something else. But that is almost always what has to happen. You need to attack from a different angle.
It may pain you to wipe out a whole page explaining a scene in favor of a line of dialogue that references the event you're talking about, but it might just be the thing that fixes your story. You know the story in intimate detail, so it's hard for you to let go of parts of it for the sake of your writing. But when you think like a reader would, you might find that your glorious scene is unnecessary exposition that bloats your story without truly advancing it.
To offer an example, you may have a scene where your main character falls out of a tree when he's a kid. You describe branches cracking, bones cracking, the aftermath at the hospital, etc. If the point you're trying to convey is that your character is afraid of heights, you might find yourself blocked when you're done with this flashback.
"I fell out of a tree when I was a kid" explains the same thing, granted without as much detail. But the explanation is enough for most readers to at least understand and rationalize the fear of heights without launching into a flashback from which there is no good transition back.
With either type of writer's block I've described, you're frustrated and need to try something different to fix it. These are ways I have found worked for me in the past, perhaps they will help you too.