When the Wicked Witch of the Blank Page (or screen) shows up and turns your brain into mush, it can be really hard to keep your bottom in the chair and come up with something so that you can honestly say you wrote today.
However, no matter how much she waves that wand around, there are a number of things you can do to drop the metaphorical house on her head and squash her flat.
One of my favorites is the "what's next" technique.
If you take a look at the scene you're working on right now and haven't a clue as to what to do with it or how it should go, start making notes or a list of what is going to happen later. This can be the very next scene or even later in the story. Chances are you have at least a glimmer of what's going to happen down the line. It doesn't have to be super concrete or written down. Even a vague idea about what you think might happen down the line will work.
Write a one line note at the top of the page (or screen) about what's coming up. (Yes, it can be longer. If it gets you on a roll, then that's even better.)
Now that you know what's going to happen in the future, consider what needs to happen before that in order for the upcoming action to occur. For instance, maybe you need to plant a clue in order for it to make its appearance later. Or consider what might be the missing step that needs to happen in order for the later scene to make sense.
A good way to get this going is to start writing (or typing): "So I know that at some point, [character's name] is going to do __________________, which means that in this scene, ______________________" Fill in the blanks (in writing) and keep going.
Or ask yourself, if Character A is going to be doing X in the future, what would she need to do before that? What would she be likely to do next? If Character B is going to be doing Y in the next chapter, what would make sense for him to do here?
You don't even have to actually write the scene. Just write about the scene and some possible things you could do with it or directions in which you could go.
As you're brainstorming (on paper), consider other ways to express or accomplish what you're trying to do in that scene. Often the first thing we come up with is the obvious. Noodle on five possible ways the scene could play out and see what shows up.
The important thing is to put all your notes and brainstorming on paper. Then you'll have something to work with. It might be a great idea or story, but if it stays in your head, no one is every going to read it.