Know what you write. Go back and investigate a bit further on your topic, whether it be Johnlock or the conflict in DRC. Investigate and learn as much as you can about the personality of characters or the events happening in the republic. This will most likely bring more inspiration.
Make an outline. If you already had an outline, pull it out and make corrections. Add, erase, overlap, plan out your whole paper. It doesn't matter if you change it along the way, the point is that now you'll have a clearer idea of what you're doing.
Sudden character death. I am encouraging you to pull a Moffat and suddenly kill off a character. You don't have to keep it this way, but writing emotionally stressing scenes may let out emotions into your writing and maybe, if you're a bit like Mark Gatiss, bring you pleasure over thinking about the readers pain.
Do some editing. Go back to the beginning of your work and start working on your editing process, even if you're not even halfway through the story. Correct your mistakes and fix some loose ends. Looking back on your plot may bring new ideas for the continuation.
Kill off your lovelies. If there is a particular character or event you feel proud of, the most likely scenario is that you shouldn't have it there. Kill it off, erase it, leave it like that or re-do it.
Put yourself in the shoes of the reader and come up with a list of questions they may ask, and answer them in your writing. Make sure your reader is left with no major doubts other than those you intended to leave hanging in the story.
Create a complex backstory to one of your minor characters. They may not matter much in the story itself, but writing a backstory and personality for a character which you may not have had many ideas about in the beginning will let you loosen up the creativity for other character writing.
Find your best time for writing. Some write early in the morning, other late at night. Find the time of the day in which you feel you write best in. Do this by spending a few days (preferably vacation or weekend days) trying to write at different times. Record how comfortable and inspired you feel at each, and finally determine which one works best for you.
Break your story into smaller parts. Divide it into sections, and write one bit each day. This way the work load will be diminished and you will feel under less pressure.
Lower the lighting of your screen. Some laptops have the feature to lower the light your screen lets out. Lower it as much as you can, so you're not able to see what you type. This way you prevent endless edits to your work.
Read some stories or fanfictions. Reading other author's work can help inspire yourself to write and get it published.
Stop writing for your readers. Write for yourself. Don't think about what the public will think, but rather write something you will feel good about, something you'll be proud about and think 'yes, I wrote that'. Don't write to please others, write to please yourself.
Lay down and listen to music. Let your mind flow away into world inspired by the lyrics of the songs. I personally sit down and listen to Josh Groban, his voice tends to take me to emotional situations, and I use those feelings to vent out into my writing. (I mostly write angst, whoops).
Stare intensely at your work for a few minutes. I've done this before, I like to call it the 'empty stare' or the 'Sherlock sulk'. Just sit, stare at your paper and think. Let the thoughts race into your head until you find one that works for you, and get back to writing.
Take an old notebook, close down your computer, and write. It doesn't have to be related to your story, just any outpouring thoughts. At least some of those thoughts will have to do with your story, right?
Write about uncomfortable things. If there's a certain topic which is uncomfortable for you to write about, such as your high school prom or sex, try writing about it. Sure, it'll feel a bit awkward, but it'll force your brain to work harder to get something onto the page, making it easier for you to write about the more normal things.
Try one of those daily challenges, such as the 30 day OTP challenge. If you simply can't write for your book/multi-chapter fic at the moment work on your daily OTP minific.
Remember all those writing tips your English teacher always gave you which you thought you'd probably never use? Use them. Go back to your old Middle School notebooks and look through the writing tips and the writing process. Apply them to your work.
Consider your setting. Change it, play with it. Move the setting from a High School AU to a USS Enterprise Ship in space. After all, why not? It is your story after all.
Write short stories to keep to yourself. Don't show them to anyone, just keep them stored away to take a look at when you feel like you can't accomplish anything.
Keep a document with easy writing ideas. Some people, like me, have simple kickstarters which always manage to get our brains working immediately with ideas. Keep a document full of these, or just words that may invite your brain to develop backstories.
Make your descriptions better, give the reader the feeling of 'show not tell'. Instead of writing 'it was a red room' describe the colour, the feeling of the room. "It had walls as red as blood, the angry paint strokes of a lovers' passion wiped all across the ceilings, the shelves, windows. It was a sea of red, of despair, of lost love".
Go into writing programs. Some programs such as NaNoWriMo offer programs and interviews with bestselling authors who tell you the way to keep active in your writing and how to beat writer's block. I guarantee their tips will be better than mine.
Make a family tree, or a relationship tree. Build it up nice and neat on a sheet of paper and start connecting every character to each other. Try to keep it simple, don't make one mans companion be the mother of his wife who is actually daughter of time. (River Song, ease up with your complicated plot line).
Keep a character locked up somewhere. Make them go away for a while, specially those frustrating characters. If Supernatural could get away with leaving Adam in the cage, so can you!
Tips for Writer's Block
Start from the beginning
