I know something like that feeling... When I feel like that it's definitely because of stress. I put a lot of pressure on myself and sometime that causes revulsion to school things, particularly the big things like papers and projects. I find that it does help to break things into tiny pieces (like other people mentioned above). And sometimes, if I feel really unable to focus, it's good to take a step back - read something else, exercise, go for a walk, or watch some tv - this will helps refresh my mind.

Hope this helps! I'm sorry you're struggling - that can be SO frustrating!! Best of luck!