Use this website http://writeordie.com/#Web+App. Right now. Set your word goal at 1000 and leave the other settings alone. Hit "write" and don't stop until the timer runs out. You might end up with something, or you might end up with jibberish. Either way you have words on the page.
Writer's block doesn't exist, it's you giving yourself excuses to not write. Doctors don't have doctor's block, plumbers don't have plumber's block. Writer's don't have writer's block, they have excuses.
Set the timer, write the words, see where the story goes. Even if it ends up being totally ridiculous. If it doesn't work, write the ending again.
A less aggressive alternative is to set a kitchen timer for an hour. Sit at your computer or with a piece of paper. You don't have to write but you can't do anything else, no doodling, poetry, or character outlines. You have to write or sit there.
"No tears in the writer, no tears in the reader. No surprise in the writer, no surprise in the reader." -Robert Frost