Writer's Block is that dreaded beast that a lot of writers are forced at one time or another to tackle. And so the questions arises, what to do? If you're stuck at that keyboard just staring off into space with this brick wall between you and your ideas, then how can you get past that? Speaking from the point of view of someone who has never had that brick wall, perhaps a few of my tips and tricks can help you get past your own.
The first way of getting past writer's block is to avoid it in the first place. Get organized. Before I start any book I always have an outline first. Have some notes down on how it beginnings, ends, and enough notes of what happens in between to connect the two ends. It needn't be all that detailed, but should be enough to plan things around as you write. When in the course of the writing you get some spontaneous ideas, then after checking to make sure if it does not violate your basic structure, or if it needs some minor adjustments to fit in, then by all means use it. I've had characters that invented themselves that way; they did nothing to take away from my basic plot, and in fact even added to it. Having an outline will prevent such roadblocks as "how do I end this?" That is the sort of question you should have ironed out before you even start, so you don't lose momentum from your writing
Another thing is your environment. I personally cannot write in silence; it just sets my mind to wandering too much and myself wriggling in my chair. Music. Put on some music, whatever kind gets you going, and it will help you focus. Something that fits the type of story you are writing. A tip, though, stick with something without lyrics, otherwise you might pay more attention to the words in the song than the ones in your head. For me, it's movie soundtracks that does it; think Star Wars and John Williams as a prime example.
If your brain is really stuck, and even when it isn't, just remember to program some downtime into your daily writing schedule. There is this support system for your brain called the Body, and if it starts wearing out then so will the brain attached to it. Get out into the world, bike, walk around, hike, walk around the local Arboretum, see a movie, whatever. A lot of ideas come from just letting your mind wander freely. Get out into the world around you and you never know what sight or sound might trigger something. Just remember that relaxation is part of the process too. Regular jobs may go from 9 to 5, but for a writer that "off time" is as important a part of the job as is sitting down at that keyboard.
Still stuck on a scene? Then let a little logic into the mix. Picture yourself as the operative character, looking at the scene around you and the problem before you, then simply ask yourself, "What would I do given this situation?" Just start logically extrapolating cause and effect until you come to a point where the Imagination starts to kick in again. A story may start with the imagination, but you have another half of your brain that's good at logic and problem solving so use it. The best writers are whole-brained, not only left or right.
And finally, you have to love what you write. The worst piece of advice I ever heard come out of a known author was "Write the market", but if all writers wrote the "market" then where would the new stuff come from? We'd never get past the urban vampire youth. The best piece of advice I can give anyone, is write your soul, write what you love. Whichever genre that happens to be, if it's something that you love, something that really excites you, then you'll be doing your best. If you write something you hate, or merely tolerate because that's what "people want", then you can't possibly do your best. But get into a story that has you as excited as a kid, gets your blood pumping, then it will flow like Niagra Falls and that brick wall between you and your ideas will never stand a chance.