Sometimes all you need to do to jump start your writing is to start a branching diagram. If you need to write about computers, write down a list of things you will need to write about under computers and continue to branch outwards until you have a good twenty or so words. Then take those words and write a sentence for each word. Once you are done, you will notice the skeleton of an article. A little polishing and transitioning between thoughts, and you are done.
Other times when a branching diagram does not work, start writing something else. Writing about your day in a journal, or even a simple as writing about something you are more interested in working on, you can take the energy from that first bit of writing and transfer it over to the writing you need to do.
One of the best ways to get creative and concentrate is to move your writing to another location. Some people find it helps if they go somewhere quiet like a park, or forest. Other people find it helps to move to an area with life, like a cafe, or in a busy book store. I personally feel more energetic and creative when I am surrounded by the energy and white noise of a large group of people.
The final tip I have for getting the words flowing is to read. When I read books I love, it inspires me to write my own works, though sometimes even just reading the newspaper, and the good and bad things going on in the world gets me in the mood to write something new.
There are always ways to get the creative juices flowing, you just have to invest a little time and energy into making it happen, though don’t stress yourself out if it does not happen. Stress can make it even harder to concentrate and be creative. Enjoy your break from writing and enjoy the days where the words come to you endlessly.