One sentence at a time. The block isn't going to magically disappear. So write one sentence/paragraph/page and then go and do something else. Come back to it and edit it. Sometimes it is just a writing block because you can't work out what the character's next move would be.
Sometimes I can't write because another story is wanting their turn. Get it out. I once wrote 15k on a story in 3 days just to get it "out" so I could go back to my original story. One day I may go back and finish off that 15k story, but at the moment it is sitting there unfinished.