Writer's Block is a frequent visitor to most writers. But how long it stays is completely up to the writer. I like to show it to the door as soon as it appears. Everyone has their way of chasing it away. Re-reading, editing, and character charts sometimes helps me get rid of Writer's Block.
I personally find word wars helpful. Word wars are when two or more people agree to write for a certain amount of time and at the end of that time they calculate how many words they wrote. Whoever writes the most wins, but winning is not really the point, its to motivate others to write. You can also do these by yourself and try and beat your own goals.
Another effective method I have found is discussing the novel, scene, or character you are struggling with. There have been several times where I am frustrated with not being able to write. I found a friend willing to listen and I explained what was going on. As I talked, ideas formed. We exchanged opinions and suggested different things. By the end of the conversation, my creative juices were at work. Perhaps it is the fact you have to make things so clear for someone else to understand that you in turn understand it better.
So how do you conquer Writer's Block?