Lots of good suggestions, if they turn out to be the ones that work for you in this instance. Copy and paste them to a separate file so when this happens again (and it will, so don't be discouraged) you have a plan of attack.
Along the lines of the above, a way that works for me is to disect what it is that I am trying to accomplish in a given moment. What aspect am I having problems developing at that specific time. I can then either feel a spark or move on without my subconscience obsessing over what it is that had been giving me trouble. Add a placeholder-
When the world was young, the barbarian (CHARACTER NAME) moved through it like a whirlwind. His (CHARACTER DESCRIPTION). When he was merely a child he...
-and write around the elements that have become obstacles. Often while you are continuing something will strike you and you can return to the obstacle and eliminate it. If you come to an end and find you have not been inspired, do something else. It's important to stay near where you can get back at it if something strikes you. Do not look on whatever else you do as anything more than a diversion so that you can drop it and return to writing quickly, at a moment's notice. Try not to choose a diversion that will absorb the same aspects of your focus. Do the dishes, paint a miniature, clean out a drawer of your desk, or juggle. Do not watch television, surf the web, or read a book. Those things generally require parts of your mind that should be left alone to recharge. Do something that allows your mind the freedom to drift back to what you are really trying to accomplish.
In summary, continue writing something else, if you can. If you cannot continue writing, do something that allows your mind to relax and allows it to return easily to writing.
