Now, everybody's different. My brain probably works differently than yours. These are cures for writer's block that worked for me and will probably work for you --- but I'm not guaranteeing anything. Try these, but feel free to make up your own. It never hurts to attempt. :)
1 --- Take A Break.
This is probably the easiest of them all. Take a week off, or at least a few days. Don't think about the perils your character is facing or will face in the next chapter. Focus on your life, not theirs. Go outside and fiddle around with photography. Draw a picture. Play a game with your sibling, if you have one. Try, especially, to do all of this outside. At least for me, fresh air helps me think --- it clears my head. :) Who knows? Something you see might trigger some creativity and cause it to leak through that giant, uncomfortable wall.
2 --- Try Writing Something New.
Don't write anything pertaining to your story. Don't even worry about having a good plot or even firm characters. Just write, for the fun of it. Write about something completely random --- for instance, write about the clothes in your closet suddenly running off and having an adventure in Fashion Land. Write about your little brother as a prince defending the Candy Princess from the evil Vegetable Monster. Anything and everything.
Sit down and write the opening of a story plot that's been floating in the back of your mind for a while. Don't worry about making a title or even chapters. Just get all the clutter that's blocking your creativity flow out of your head. :)
3 --- Write Opposites.
Write something in a completely different genre than you normally would. Now this --- this is hard. Fantasy is my normal genre, but if I tried writing something like a history textbook, I'd be bored to death. History fiction is okay .... mysteries? Forget it!
If you can't think of another genre to write in, try twisting your story around. Change your main character's personality drastically. Make her a brat or a pop star. If your story is set in a fantasy land, try writing it set in a busier place, like Manhattan or Los Angeles. Tell your story from the bad guy's perspective. Or tell it from a child's perspective. Just use a different perspective, and make sure you do this on a separate file and not on your actual story. That would be bad. (:
4 --- Don't Be Normal.
Do something totally different than what you normally do.
If you like fantasy (like me) try reading something different: history fiction novel. Mystery book. Even a how-to book.
Try something you wouldn't normally try: exotic foods, maybe, or listen to different music. I like to listen to my favorite movie soundtracks --- Pirates of the Caribbean, mostly. :) It helps me focus and creates images in my head that normally help me climb over the wall.
Watch something you wouldn't normally watch. A sci-fi movie. A chick flick. A spy blockbuster. Anything out of the ordinary for you to do. :)
I hope this helps with the extremely large, difficult wall called Writer's Block. These are my methods. What are yours? :)